CN111817132A - Modulated Laser Diode Improved Structure - Google Patents

Abstract

An improved structure of a modulated laser diode includes a semiconductor substrate and a distributed feedback laser formed on the semiconductor substrate. The distributed feedback laser is divided into a front end and a rear end. The distributed feedback laser includes a lower semiconductor layer, an active layer, an upper semiconductor layer, a front grating, and a rear grating from bottom to top. The front grating is formed in the lower semiconductor layer or the upper semiconductor layer of the front end of the distributed feedback laser. The rear grating is formed in the lower semiconductor layer or the upper semiconductor layer of the rear end of the distributed feedback laser. A grating length of the front grating is greater than or equal to a grating length of the rear grating. A grating period of the front grating is equal to a grating period of the rear grating. A grating duty period of the front grating is greater than or equal to 40% and less than or equal to 60%. A grating duty period of the rear grating is greater than 0% and less than 40% or greater than 60% and less than 100%.

Description

Modulated Laser Diode Improved Structure

technical field

The present invention relates to a modulation laser diode, in particular to a modulation laser diode with an anti-reflection structure.

Background technique

Please refer to FIG. 6 , which is a specific embodiment of a modulated laser diode in the prior art. The modulation laser diode in the prior art is an Electroabsorption Modulation Laser (EML) diode, which includes a semiconductor substrate 90 , a distributed feedback laser 9 , and an electro-optical absorption modulator 96 (EAM). : Electroabsorption Modulator), an anti-reflection coating (Anti-reflection coating) 94 and a high reflection coating (High reflection coating) 95. The distributed feedback laser 9 and the electro-optical absorption modulator 96 are formed on the semiconductor substrate 90 . The distributed feedback laser 9 includes an n-type semiconductor layer 91 , an active layer 92 , a p-type semiconductor layer 93 and a diffraction grating 97 . The n-type semiconductor layer 91 is formed on the semiconductor substrate 90 ; the active layer 92 is formed on the n-type semiconductor layer 91 ; the p-type semiconductor layer 93 is formed on the active layer 92 . Among them, the diffraction grating 97 is formed in the p-type semiconductor layer 93 . The anti-reflection film 94 is formed on the front end of the electro-optical absorption modulator 96 . The high reflection film 95 is formed at the rear end of the distributed feedback laser 9 . The diffraction grating 97 has a diffraction grating period P9 and a diffraction grating duty cycle D9/P9 (duty cycle). The duty cycle D9/P9 of the diffraction grating is equal to 50%. In the design of the modulated laser diode in the prior art, the laser light is output from the front end of the electro-optical absorption modulator 96 . Although there is an anti-reflection film 94 at the front end of the electro-optical absorption modulator 96 to suppress the reflection of the laser light, a small part of the laser light is still reflected back to the electro-optical absorption modulator 96 and the distributed feedback laser 9, and then The high reflection film 95 at the rear end of the distributed feedback laser 9 is then reflected back to the distributed feedback laser 9 and the electro-optical absorption modulator 96, so that the output power of the laser will oscillate violently with time (see FIG. 2M later). ).

In view of this, the inventor of the present application has developed a design that is easy to assemble, can avoid the above shortcomings, is easy to install, and has the advantages of low cost, so as to take into account the flexibility of use and economy, and thus the invention is born.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is how to effectively reduce the oscillation amplitude of the laser output power of the modulated laser diode with time.

In order to solve the aforementioned problems and achieve the desired effect, the present invention provides an improved structure of a modulated laser diode, which includes a semiconductor substrate and a distributed feedback laser. The distributed feedback laser is formed on the semiconductor substrate. The distributed feedback laser is divided into a front end and a rear end. The distributed feedback laser includes a lower semiconductor layer, an active layer, an upper semiconductor layer, a front-end diffraction grating and a first rear-end diffraction grating. The lower semiconductor layer is formed on the semiconductor substrate; the lower semiconductor layer is formed on the semiconductor substrate; and the upper semiconductor layer is formed on the active layer. The front-end diffraction grating is formed in the lower semiconductor layer or the upper semiconductor layer at the front end of the distributed feedback laser, the front-end diffraction grating has a front-end diffraction grating length, and the front-end diffraction grating has a front-end diffraction grating period and a Front-end diffraction grating duty cycle. The first rear diffraction grating is formed in the lower semiconductor layer or the upper semiconductor layer at the rear end of the distributed feedback laser, the first rear diffraction grating has a first rear diffraction grating length, and the first rear diffraction grating has a first rear diffraction grating length. The end diffraction grating has a first back end diffraction grating period and a first back end diffraction grating duty period. The length of the front-end diffraction grating is greater than or equal to the length of the first back-end diffraction grating, the period of the front-end diffraction grating is equal to the period of the first back-end diffraction grating, and the duty period of the front-end diffraction grating is greater than or equal to 40% and less than or equal to 60 %, the duty cycle of the first back-end diffraction grating (1) is greater than 0% and less than 40%, or (2) is greater than 60% and less than 100%. Thereby, the oscillation amplitude of the laser output power of the modulated laser diode of the present invention with time is effectively reduced.

In one embodiment, a distance between the front-end diffraction grating and the active layer is equal to a distance between the first rear-end diffraction grating and the active layer.

In one embodiment, (1) the front-end diffraction grating is formed in the lower semiconductor layer of the front-end portion of the distributed feedback laser, and the first rear-end diffraction grating is formed in the upper semiconductor layer of the rear-end portion of the distributed feedback laser layer, wherein the distributed feedback laser further includes a second rear-end diffraction grating, wherein the second rear-end diffraction grating is formed in the lower semiconductor layer at the rear end of the distributed feedback laser, or (2) front-end diffraction grating The grating is formed in the upper semiconductor layer of the front end of the distributed feedback laser, and the first rear diffraction grating is formed in the lower semiconductor layer of the rear end of the distributed feedback laser, wherein the distributed feedback laser further includes a second Back-end diffraction grating, wherein the second back-end diffraction grating is formed in the upper semiconductor layer of the rear end of the distributed feedback laser; wherein a distance between the second back-end diffraction grating and the active layer is equal to the front-end diffraction grating The distance between the grating and the active layer, wherein the second back-end diffraction grating has a second back-end diffraction grating length, wherein the second back-end diffraction grating has a second back-end diffraction grating period and a second back-end diffraction grating The duty cycle of the back-end diffraction grating, wherein the length of the second back-end diffraction grating is equal to the length of the first back-end diffraction grating, wherein the period of the front-end diffraction grating is equal to the period of the second back-end diffraction grating, wherein the second back-end diffraction grating is equal to the period of the second back-end diffraction grating The radiation grating duty cycle is equal to 100%.

In one embodiment, a distance between the front-end diffraction grating and the active layer is smaller than a distance between the first rear-end diffraction grating and the active layer.

In one embodiment, (1) the front-end diffraction grating is formed in the upper semiconductor layer of the front-end portion of the distributed feedback laser, and the first rear-end diffraction grating is formed in the upper semiconductor layer of the rear-end portion of the distributed feedback laser layer, wherein the distributed feedback laser further includes a second rear-end diffraction grating, wherein the second rear-end diffraction grating is formed in the upper semiconductor layer of the rear end of the distributed feedback laser, and the second rear-end diffraction grating The grating is located between the first back-end diffraction grating and the active layer; (2) the front-end diffraction grating is formed in the upper semiconductor layer of the front-end portion of the distributed feedback laser, and the first back-end diffraction grating is formed in the distributed feedback laser In the lower semiconductor layer of the rear end of the laser, the distributed feedback laser further includes a second rear diffraction grating, wherein the second rear diffraction grating is formed in the upper semiconductor layer of the rear end of the distributed feedback laser (3) The front-end diffraction grating is formed in the lower semiconductor layer of the front-end portion of the distributed feedback laser, and the first rear-end diffraction grating is formed in the lower semiconductor layer of the rear-end portion of the distributed feedback laser, wherein the distributed feedback laser The feedback laser further includes a second back-end diffraction grating, wherein the second back-end diffraction grating is formed in the lower semiconductor layer at the back end of the distributed feedback laser, and the second back-end diffraction grating is located at the first back-end between the diffraction grating and the active layer; or (4) the front-end diffraction grating is formed in the lower semiconductor layer of the front-end portion of the distributed feedback laser, and the first rear-end diffraction grating is formed at the back-end portion of the distributed feedback laser In the upper semiconductor layer of the distributed feedback laser, the distributed feedback laser further includes a second rear-end diffraction grating, wherein the second rear-end diffraction grating is formed in the lower semiconductor layer at the rear end of the distributed feedback laser; A distance between the end diffraction grating and the active layer is equal to the distance between the front end diffraction grating and the active layer, wherein the second back end diffraction grating has a second back end diffraction grating length, wherein the second back end diffraction grating has a length. The diffraction grating has a second back-end diffraction grating period and a second back-end diffraction grating duty period, wherein the length of the second back-end diffraction grating is equal to the length of the first back-end diffraction grating, and the front-end diffraction grating period is is equal to the second back-end diffraction grating period, wherein the second back-end diffraction grating duty period is equal to 100%.

In one embodiment, the duty cycle of the first back-end diffraction grating is (1) greater than 0% and less than or equal to 25%, or (2) greater than or equal to 75% and less than 100%.

The present invention further provides an improved structure of a modulated laser diode, comprising a semiconductor substrate and a distributed feedback laser. The distributed feedback laser is formed on the semiconductor substrate. The distributed feedback laser is divided into a front end and a rear end. The distributed feedback laser includes a lower semiconductor layer, an active layer, an upper semiconductor layer, a front-end diffraction grating and a first rear-end diffraction grating. The lower semiconductor layer is formed on the semiconductor substrate; the lower semiconductor layer is formed on the semiconductor substrate; and the upper semiconductor layer is formed on the active layer. The front-end diffraction grating is formed in the lower semiconductor layer or the upper semiconductor layer at the front end of the distributed feedback laser, the front-end diffraction grating has a front-end diffraction grating length, and the front-end diffraction grating has a front-end diffraction grating period and a Front-end diffraction grating duty cycle. The first rear diffraction grating is formed in the lower semiconductor layer or the upper semiconductor layer at the rear end of the distributed feedback laser, the first rear diffraction grating has a first rear diffraction grating length, and the first rear diffraction grating has a first rear diffraction grating length. The end diffraction grating has a first back end diffraction grating period and a first back end diffraction grating duty period. The length of the front-end diffraction grating is greater than or equal to the length of the first back-end diffraction grating, wherein the period of the front-end diffraction grating is equal to the period of the first back-end diffraction grating, and the duty period of the front-end diffraction grating is greater than or equal to 40% and less than or is equal to 60%, wherein a distance between the front-end diffraction grating and the active layer is smaller than a distance between the first rear-end diffraction grating and the active layer. Thereby, the oscillation amplitude of the laser output power of the modulated laser diode of the present invention with time is effectively reduced.

In one embodiment, the duty cycle of the first rear-end diffraction grating is greater than or equal to 40% and less than or equal to 60%.

In one embodiment, (1) the front-end diffraction grating is formed in the upper semiconductor layer of the front-end portion of the distributed feedback laser, and the first rear-end diffraction grating is formed in the upper semiconductor layer of the rear-end portion of the distributed feedback laser layer, wherein the distributed feedback laser further includes a second rear-end diffraction grating, wherein the second rear-end diffraction grating is formed in the upper semiconductor layer of the rear end of the distributed feedback laser, and the second rear-end diffraction grating The grating is located between the first back-end diffraction grating and the active layer; (2) the front-end diffraction grating is formed in the upper semiconductor layer of the front-end portion of the distributed feedback laser, and the first back-end diffraction grating is formed in the distributed feedback laser In the lower semiconductor layer of the rear end of the laser, the distributed feedback laser further includes a second rear diffraction grating, wherein the second rear diffraction grating is formed in the upper semiconductor layer of the rear end of the distributed feedback laser (3) The front-end diffraction grating is formed in the lower semiconductor layer of the front-end portion of the distributed feedback laser, and the first rear-end diffraction grating is formed in the lower semiconductor layer of the rear-end portion of the distributed feedback laser, wherein the distributed feedback laser The feedback laser further includes a second back-end diffraction grating, wherein the second back-end diffraction grating is formed in the lower semiconductor layer at the back end of the distributed feedback laser, and the second back-end diffraction grating is located at the first back-end between the diffraction grating and the active layer; or (4) the front-end diffraction grating is formed in the lower semiconductor layer of the front-end portion of the distributed feedback laser, and the first rear-end diffraction grating is formed at the back-end portion of the distributed feedback laser In the upper semiconductor layer of the distributed feedback laser, the distributed feedback laser further includes a second rear-end diffraction grating, wherein the second rear-end diffraction grating is formed in the lower semiconductor layer at the rear end of the distributed feedback laser; A distance between the end diffraction grating and the active layer is equal to the distance between the front end diffraction grating and the active layer, wherein the second back end diffraction grating has a second back end diffraction grating length, wherein the second back end diffraction grating has a length. The diffraction grating has a second back-end diffraction grating period and a second back-end diffraction grating duty period, wherein the length of the second back-end diffraction grating is equal to the length of the first back-end diffraction grating, and the front-end diffraction grating period is is equal to the second back-end diffraction grating period, wherein the second back-end diffraction grating duty period is equal to 100%.

In one embodiment, the lower semiconductor layer is an n-type semiconductor layer.

In one embodiment, the upper semiconductor layer is a p-type semiconductor layer.

In one embodiment, the modulated laser diode is a direct modulated laser diode.

In one embodiment, it further includes an electro-optical absorption modulator, wherein the electro-optical absorption modulator is formed on the semiconductor substrate, and the front end of the distributed feedback laser is located at the rear end of the distributed feedback laser and between the electro-optical absorption modulators, wherein the modulation laser diode is an electro-optical absorption modulation laser diode.

In one embodiment, the ratio of the length of the front-end diffraction grating to the length of the first back-end diffraction grating is greater than or equal to 1 and less than or equal to 4.

In order to further understand the present invention, the preferred embodiments are given below, and the specific components of the present invention and the effects achieved are described in detail as follows in conjunction with the drawings and drawing numbers.

Description of drawings

1A is a schematic cross-sectional view of a specific embodiment of an improved structure of a modulated laser diode according to the present invention.

1B is a schematic cross-sectional view of a specific embodiment of an improved structure of a modulated laser diode according to the present invention.

2A-2L are schematic cross-sectional views of a specific embodiment of a distributed feedback laser with an improved structure of a modulated laser diode according to the present invention.

FIG. 2M is a graph comparing the variation of output power with time between a specific embodiment of an improved structure of a modulated laser diode according to the present invention and a specific embodiment of the prior art.

FIG. 2N is a graph comparison of output power versus time of a specific embodiment of an improved structure of a modulating laser diode according to the present invention.

3A to 3H are schematic cross-sectional views of a specific embodiment of a distributed feedback laser with an improved structure of a modulated laser diode according to the present invention.

4A to 4H are schematic cross-sectional views of a specific embodiment of a distributed feedback laser with an improved structure of a modulated laser diode according to the present invention.

5A-5H are schematic cross-sectional views of a specific embodiment of a distributed feedback laser with an improved structure of a modulated laser diode according to the present invention.

FIG. 6 is a specific embodiment of a modulated laser diode in the prior art.

Description of reference numerals: 1-distributed feedback laser; 2-front end of distributed feedback laser; 3-back end of distributed feedback laser; 4-electro-optical absorption modulator; 10-semiconductor substrate; 20- Lower semiconductor layer; 30-active layer; 40-upper semiconductor layer; 50-front-end diffraction grating; 51-first back-end diffraction grating; 52-second back-end diffraction grating; 6-anti-reflection film; 7- High reflection film; 9-distributed feedback laser; 90-semiconductor substrate; 91-n-type semiconductor layer; 92-active layer; 93-p-type semiconductor layer; 94-anti-reflection film; 95-high-reflection film; 96-electrical Optical absorption modulator; 97-diffraction grating; D0/P0- the duty period of the front-end diffraction grating; D1/P1- the duty period of the first back-end diffraction grating; D2/P2- the second back-end diffraction grating duty cycle; D9/P9-diffraction grating duty cycle; L0-front-end diffraction grating length; L1-first back-end diffraction grating length; L2-second back-end diffraction grating length; P0-front-end diffraction grating length Diffraction grating period; P1-the first back-end diffraction grating period; P2-the second back-end diffraction grating period; P9-diffraction grating period; X0-the distance between the front-end diffraction grating and the active layer; X1-the first back-end diffraction grating The distance between the end diffraction grating and the active layer; X2 - the distance between the second rear end diffraction grating and the active layer.

Detailed ways

Please refer to FIG. 1A , which is a schematic cross-sectional view of a specific embodiment of an improved structure of a modulated laser diode according to the present invention. The modulated laser diode of this embodiment is a Direct Modulation Laser (DML) diode, which includes a semiconductor substrate 10 , a distributed feedback laser 1 , an anti-reflection film 6 and a high-reflection film 7 . The distributed feedback laser 1 is formed on the semiconductor substrate 10 . The distributed feedback laser 1 is divided into a front end 2 and a rear end 3 . The anti-reflection film 6 is formed at the front end of the front end portion 2 of the distributed feedback laser 1 ; and the high reflection film 7 is formed at the rear end of the rear end portion 3 of the distributed feedback laser 1 . The laser light is output from the front end of the front end portion 2 of the distributed feedback laser 1 . Please refer to FIGS. 2A to 2L, 3A to 3H, 4A to 4H, and 5A to 5H for cross-sectional schematic diagrams of specific embodiments of a distributed feedback laser with an improved structure of a modulated laser diode according to the present invention. . The detailed structure of the distributed feedback laser 1 in the embodiment of FIG. 1A can be the same as the distribution in any of the embodiments of FIGS. 2A to 2L, 3A to 3H, 4A to 4H, and 5A to 5H. The structure of the feedback laser 1 is the same.

Please refer to FIG. 1B , which is a schematic cross-sectional view of a specific embodiment of an improved structure of a modulated laser diode according to the present invention. The modulated laser diode of this embodiment is an electro-optical absorption modulated laser diode, including a semiconductor substrate 10 , a distributed feedback laser 1 , an electro-optical absorption modulator 4 , an anti-reflection film 6 and a high Reflective film 7. The distributed feedback laser 1 and the electro-optical absorption modulator 4 are formed on the semiconductor substrate 10 . The distributed feedback laser 1 is divided into a front end 2 and a rear end 3 . The front end 2 of the distributed feedback laser 1 is located between the rear end 3 of the distributed feedback laser 1 and the electro-optical absorption modulator 4 . The anti-reflection film 6 is formed at the front end of the electro-optical absorption modulator 4 ; and the high-reflection film 7 is formed at the rear end of the rear end portion 3 of the distributed feedback laser 1 . The laser light is output from the front end of the electro-optical absorption modulator 4 . Please refer to FIGS. 2A to 2L, 3A to 3H, 4A to 4H, and 5A to 5H for cross-sectional schematic diagrams of specific embodiments of a distributed feedback laser with an improved structure of a modulated laser diode according to the present invention. . The detailed structure of the distributed feedback laser 1 in the embodiment of FIG. 1B can be the same as the distribution in any of the embodiments of FIGS. 2A to 2L, 3A to 3H, 4A to 4H, and 5A to 5H. The structure of the feedback laser 1 is the same.

Please refer to FIG. 2A , which is a schematic cross-sectional view of a specific embodiment of a distributed feedback laser with an improved structure of a modulated laser diode according to the present invention. In this embodiment, an improved structure of a modulated laser diode of the present invention includes a semiconductor substrate 10 and a distributed feedback laser 1 . The distributed feedback laser 1 is formed on the semiconductor substrate 10 . The distributed feedback laser 1 is divided into a front end 2 and a rear end 3 . The distributed feedback laser 1 includes a lower semiconductor layer 20 , an active layer 30 , an upper semiconductor layer 40 , a front-end diffraction grating 50 and a first rear-end diffraction grating 51 . The lower semiconductor layer 20 is formed on the semiconductor substrate 10 , wherein the lower semiconductor layer 20 is an n-type semiconductor layer. The active layer 30 is formed on the lower semiconductor layer 20 . The upper semiconductor layer 40 is formed on the active layer 30 , wherein the upper semiconductor layer 40 is a p-type semiconductor layer. The front-end diffraction grating 50 is formed in the upper semiconductor layer 40 of the front-end portion 2 of the distributed feedback laser 1, wherein the front-end diffraction grating 50 has a front-end diffraction grating length L0, and the front-end diffraction grating 50 has a front-end diffraction grating The period P0 and a front-end diffraction grating are responsible for the period D0/P0. The first rear-end diffraction grating 51 is formed in the upper semiconductor layer 40 of the rear-end portion 3 of the distributed feedback laser 1 . The first rear diffraction grating 51 has a first rear diffraction grating length L1. The first back-end diffraction grating 51 has a first back-end diffraction grating period P1 and a first back-end diffraction grating duty period D1/P1. A distance X0 between the front-end diffraction grating 50 and the active layer 30 is equal to a distance X1 between the first rear-end diffraction grating 51 and the active layer 30 . The length L0 of the front-end diffraction grating is greater than the length L1 of the first rear-end diffraction grating. The front-end diffraction grating period P0 is equal to the first rear-end diffraction grating period P1. The duty cycle D0/P0 of the front-end diffraction grating is greater than or equal to 40% and less than or equal to 60%. The duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than 40%. The duty period D0/P0 of the front-end diffraction grating is not equal to the duty period D1/P1 of the first rear-end diffraction grating. An improved structure of the modulated laser diode of the present invention in the embodiment of FIG. 1A or FIG. 1B may have the structure of the distributed feedback laser 1 as shown in FIG. 2A , thereby effectively reducing the laser output power of the modulated laser diode. The amplitude of the oscillations in time. In some embodiments, the front diffraction grating length L0 is equal to the first rear diffraction grating length L1. In other embodiments, the ratio of the front-end diffraction grating length L0 to the first back-end diffraction grating length L1 is greater than or equal to 1 and less than or equal to 4. In some embodiments, the duty cycle D1/P1 of the first back-end diffraction grating is greater than 0% and less than or equal to 35%. In other embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 30%. In some preferred embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 25%. In some other preferred embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 23%. In some preferred embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 20%. In some other preferred embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 18%. In some preferred embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 15%. In some other preferred embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 10%. In some preferred embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 5%.

Please refer to FIG. 2M and FIG. 2N , which are graphs comparing the output power with time of a specific embodiment of an improved structure of a modulating laser diode according to the present invention and a specific embodiment of the prior art. An improved structure of the modulated laser diode of the present invention in the embodiments of FIG. 2M and FIG. 2N is an electro-optical absorption modulated laser diode, the structure of which is shown in the embodiment of FIG. 1B , wherein the structure of the distributed feedback laser 1 is As shown in Figure 2A. In FIG. 2M, there is a special case, the structure of which the duty period D1/P1 of the first rear-end diffraction grating is equal to 50% has the same structure as the diffraction grating 97 of the prior art. In FIG. 2M, the duty cycle D1/P1 of the first rear-end diffraction grating is equal to 40%, 30%, or 20%, which is the structure of the distributed feedback laser 1 of the present invention. It can be easily observed from FIG. 2M that when the duty period D1/P1 of the first rear-end diffraction grating is equal to 50% (which has the same structure as the diffraction grating 97 of the prior art), the output power of the laser varies with time. The vibration is huge. And the structure of the distributed feedback laser 1 of the present invention (whether the duty cycle D1/P1 of the first rear-end diffraction grating is equal to 40%, D1=30%, or D1=20%), the output power of the laser The oscillation amplitude over time is significantly smaller than the oscillation amplitude of the output power over time when the duty period D1/P1 of the first rear-end diffraction grating is equal to 50% (which has the same structure as the diffraction grating 97 of the prior art). Especially when the duty cycle D1/P1 of the first back-end diffraction grating is equal to 20%, the oscillation amplitude of the output power of the laser over time is much smaller than the duty cycle D1/P1 of the first back-end diffraction grating is equal to 50%. (Has the same structure as the diffraction grating 97 of the prior art) the oscillation amplitude of the output power with time. Since when the duty period D1/P1 of the first rear-end diffraction grating is equal to 10% or 5%, the oscillation amplitude of the output power of the laser with time is too small, and the difference will not be seen if it is placed in Figure 2M, Therefore, it is also shown in FIG. 2N. It can be clearly seen from Fig. 2N that the oscillation amplitude of the output power with the duty period D1/P1 of the first back-end diffraction grating equal to 10% or 5% over time is larger than that of the duty period D1/P1 of the first back-end diffraction grating. An output power equal to 20% has a smaller oscillation amplitude over time. Therefore, an improved structure of the modulated laser diode of the present invention can indeed enhance the anti-reflection function and significantly reduce the oscillation amplitude of its optical output power with time. There is a special case in FIG. 2N, which is a situation in which there is no first rear-end diffraction grating 51 when the duty cycle D1/P1 of the first rear-end diffraction grating is equal to 0%. However, without the first back-end diffraction grating 51, the oscillation amplitude of its output power with time is greater than that of the first back-end diffraction grating duty cycle D1/P1 equal to 20%, 10%, or 5% of the output power The amplitude of the oscillations in time.

Please refer to FIG. 2B , which is a schematic cross-sectional view of a specific embodiment of a distributed feedback laser with an improved structure of a modulated laser diode according to the present invention. The main structure of the embodiment of FIG. 2B is substantially the same as that of the embodiment of FIG. 2A , except that the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 60% and less than 100%. In some embodiments, the duty cycle D1/P1 of the first back-end diffraction grating is greater than 0% and less than or equal to 65%. In other embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 70%. In some preferred embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 75%. In some other preferred embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 77%. In some preferred embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 80%. In some other preferred embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 82%. In some preferred embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 85%. In some other preferred embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 90%. In some preferred embodiments, the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 0% and less than or equal to 95%. An improved structure of the modulated laser diode of the present invention in the embodiment of FIG. 1A or FIG. 1B may have the structure of the distributed feedback laser 1 as shown in FIG. 2B , thereby effectively reducing the laser output power of the modulated laser diode over time. vibration amplitude.

Please refer to FIG. 2C to FIG. 2L , which are schematic cross-sectional views of a specific embodiment of a distributed feedback laser with an improved structure of a modulated laser diode according to the present invention. The main structure of the embodiment of FIG. 2C is substantially the same as that of the embodiment of FIG. 2A , except that the first rear-end diffraction grating 51 is formed in the lower semiconductor layer 20 of the rear-end portion 3 of the distributed feedback laser 1 , And the distance X0 between the front diffraction grating 50 and the active layer 30 is equal to the distance X1 between the first rear diffraction grating 51 and the active layer 30 . The main structure of the embodiment of FIG. 2D is substantially the same as that of the embodiment of FIG. 2C , except that the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 60% and less than 100%. The main structure of the embodiment of FIG. 2E is substantially the same as that of the embodiment of FIG. 2A , except that the front-end diffraction grating 50 is formed in the lower semiconductor layer 20 of the front-end portion 2 of the distributed feedback laser 1 , and the front-end diffraction grating 50 is wound around The distance X0 between the diffraction grating 50 and the active layer 30 is equal to the distance X1 between the first rear-end diffraction grating 51 and the active layer 30 . The main structure of the embodiment of FIG. 2F is substantially the same as that of the embodiment of FIG. 2E , except that the duty period D1/P1 of the first rear-end diffraction grating is greater than 60% and less than 100%. The main structure of the embodiment of FIG. 2G is substantially the same as that of the embodiment of FIG. 2E , except that the first rear-end diffraction grating 51 is formed in the lower semiconductor layer 20 of the rear-end portion 3 of the distributed feedback laser 1 , And the distance X0 between the front diffraction grating 50 and the active layer 30 is equal to the distance X1 between the first rear diffraction grating 51 and the active layer 30 . The main structure of the embodiment of FIG. 2H is substantially the same as that of the embodiment of FIG. 2G , except that the duty period D1/P1 of the first rear-end diffraction grating is greater than 60% and less than 100%. The main structure of the embodiment of FIG. 2I is substantially the same as that of the embodiment of FIG. 2C , except that the distributed feedback laser 1 further includes a second rear-end diffraction grating 52 . The second rear-end diffraction grating 52 is formed in the upper semiconductor layer 40 of the rear-end portion 3 of the distributed feedback laser 1 . A distance X2 between the second rear diffraction grating 52 and the active layer 30 is equal to a distance X0 between the front diffraction grating 50 and the active layer 30 . The second rear diffraction grating 52 has a second rear diffraction grating length L2. The second back-end diffraction grating 52 has a second back-end diffraction grating period P2 and a second back-end diffraction grating duty period D2/P2. The length L2 of the second rear-end diffraction grating is equal to the length L1 of the first rear-end diffraction grating. The front-end diffraction grating period P0 is equal to the second rear-end diffraction grating period P2. The duty cycle D2/P2 of the second rear-end diffraction grating is equal to 100%. The main structure of the embodiment of FIG. 2J is substantially the same as that of the embodiment of FIG. 2I , except that the duty cycle D1 / P1 of the first rear-end diffraction grating is greater than 60% and less than 100%. The main structure of the embodiment of FIG. 2K is substantially the same as that of the embodiment of FIG. 2E , but the distributed feedback laser 1 further includes a second rear-end diffraction grating 52 . The second rear-end diffraction grating 52 is formed in the lower semiconductor layer 20 of the rear-end portion 3 of the distributed feedback laser 1 . A distance X2 between the second rear diffraction grating 52 and the active layer 30 is equal to a distance X0 between the front diffraction grating 50 and the active layer 30 . The second rear diffraction grating 52 has a second rear diffraction grating length L2. The second back-end diffraction grating 52 has a second back-end diffraction grating period P2 and a second back-end diffraction grating duty period D2/P2. The length L2 of the second rear-end diffraction grating is equal to the length L1 of the first rear-end diffraction grating. The front-end diffraction grating period P0 is equal to the second rear-end diffraction grating period P2. The duty cycle D2/P2 of the second rear-end diffraction grating is equal to 100%. The main structure of the embodiment of FIG. 2L is substantially the same as that of the embodiment of FIG. 2K , except that the duty period D1/P1 of the first rear-end diffraction grating is greater than 60% and less than 100%. An improved structure of the modulated laser diode of the present invention in the embodiment of FIG. 1A or FIG. 1B can have the structure of the distributed feedback laser 1 in any of the embodiments of FIGS. 2C to 2L , thereby effectively reducing the modulation. The oscillation amplitude of the laser output power of a laser diode over time.

Please refer to FIGS. 3A to 3H , which are schematic cross-sectional views of a specific embodiment of a distributed feedback laser with an improved structure of a modulated laser diode according to the present invention. The main structure of the embodiment of FIG. 3A is substantially the same as that of the embodiment of FIG. 2A , except that the distance X0 between the front-end diffraction grating 50 and the active layer 30 is smaller than the first back-end diffraction grating 51 and the active layer 30 The distance between X1. The main structure of the embodiment of FIG. 3B is substantially the same as that of the embodiment of FIG. 3A , except that the duty period D1/P1 of the first rear-end diffraction grating is greater than 60% and less than 100%. The main structure of the embodiment of FIG. 3C is substantially the same as that of the embodiment of FIG. 2C , except that the distance X0 between the front-end diffraction grating 50 and the active layer 30 is smaller than the first rear-end diffraction grating 51 and the active layer 30 The distance between X1. The main structure of the embodiment of FIG. 3D is substantially the same as that of the embodiment of FIG. 3C , except that the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 60% and less than 100%. The main structure of the embodiment of FIG. 3E is substantially the same as that of the embodiment of FIG. 2E , except that the distance X0 between the front-end diffraction grating 50 and the active layer 30 is smaller than the first rear-end diffraction grating 51 and the active layer 30 The distance between X1. The main structure of the embodiment of FIG. 3F is substantially the same as that of the embodiment of FIG. 3E, but the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 60% and less than 100%. The main structure of the embodiment of FIG. 3G is substantially the same as that of the embodiment of FIG. 2G , except that the distance X0 between the front-end diffraction grating 50 and the active layer 30 is smaller than the first back-end diffraction grating 51 and the active layer 30 The distance between X1. The main structure of the embodiment of FIG. 3H is substantially the same as that of the embodiment of FIG. 3G , except that the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 60% and less than 100%. An improved structure of the modulated laser diode of the present invention in the embodiment of FIG. 1A or FIG. 1B can have the structure of the distributed feedback laser 1 in any of the embodiments of FIGS. 3A to 3H , thereby effectively reducing the modulation. The oscillation amplitude of the laser output power of a laser diode over time.

Please refer to FIGS. 4A to 4H , which are schematic cross-sectional views of a specific embodiment of a distributed feedback laser with an improved structure of a modulated laser diode according to the present invention. The main structure of the embodiment of FIG. 4A is substantially the same as that of the embodiment of FIG. 3A , but the distributed feedback laser 1 further includes a second rear-end diffraction grating 52 . The second rear-end diffraction grating 52 is formed in the upper semiconductor layer 40 of the rear-end portion 3 of the distributed feedback laser 1 . A distance X2 between the second rear diffraction grating 52 and the active layer 30 is equal to a distance X0 between the front diffraction grating 50 and the active layer 30 . The second rear diffraction grating 52 has a second rear diffraction grating length L2. The second back-end diffraction grating 52 has a second back-end diffraction grating period P2 and a second back-end diffraction grating duty period D2/P2. The length L2 of the second rear-end diffraction grating is equal to the length L1 of the first rear-end diffraction grating. The front-end diffraction grating period P0 is equal to the second rear-end diffraction grating period P2. The duty cycle D2/P2 of the second rear-end diffraction grating is equal to 100%. The main structure of the embodiment of FIG. 4B is substantially the same as that of the embodiment of FIG. 4A , except that the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 60% and less than 100%. The main structure of the embodiment of FIG. 4C is substantially the same as that of the embodiment of FIG. 3C , except that the distributed feedback laser 1 further includes a second rear-end diffraction grating 52 . The second rear-end diffraction grating 52 is formed in the upper semiconductor layer 40 of the rear-end portion 3 of the distributed feedback laser 1 . A distance X2 between the second rear diffraction grating 52 and the active layer 30 is equal to a distance X0 between the front diffraction grating 50 and the active layer 30 . The second rear diffraction grating 52 has a second rear diffraction grating length L2. The second back-end diffraction grating 52 has a second back-end diffraction grating period P2 and a second back-end diffraction grating duty period D2/P2. The length L2 of the second rear-end diffraction grating is equal to the length L1 of the first rear-end diffraction grating. The front-end diffraction grating period P0 is equal to the second rear-end diffraction grating period P2. The duty cycle D2/P2 of the second rear-end diffraction grating is equal to 100%. The main structure of the embodiment of FIG. 4D is substantially the same as that of the embodiment of FIG. 4C , except that the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 60% and less than 100%. The main structure of the embodiment of FIG. 4E is substantially the same as that of the embodiment of FIG. 3E , but the distributed feedback laser 1 further includes a second rear-end diffraction grating 52 . The second rear-end diffraction grating 52 is formed in the lower semiconductor layer 20 of the rear-end portion 3 of the distributed feedback laser 1 . A distance X2 between the second rear diffraction grating 52 and the active layer 30 is equal to a distance X0 between the front diffraction grating 50 and the active layer 30 . The second rear diffraction grating 52 has a second rear diffraction grating length L2. The second back-end diffraction grating 52 has a second back-end diffraction grating period P2 and a second back-end diffraction grating duty period D2/P2. The length L2 of the second rear-end diffraction grating is equal to the length L1 of the first rear-end diffraction grating. The front-end diffraction grating period P0 is equal to the second rear-end diffraction grating period P2. The duty cycle D2/P2 of the second rear-end diffraction grating is equal to 100%. The main structure of the embodiment of FIG. 4F is substantially the same as that of the embodiment of FIG. 4E , except that the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 60% and less than 100%. The main structure of the embodiment of FIG. 4G is substantially the same as that of the embodiment of FIG. 3G , except that the distributed feedback laser 1 further includes a second rear-end diffraction grating 52 . The second rear-end diffraction grating 52 is formed in the lower semiconductor layer 20 of the rear-end portion 3 of the distributed feedback laser 1 . A distance X2 between the second rear diffraction grating 52 and the active layer 30 is equal to a distance X0 between the front diffraction grating 50 and the active layer 30 . The second rear diffraction grating 52 has a second rear diffraction grating length L2. The second back-end diffraction grating 52 has a second back-end diffraction grating period P2 and a second back-end diffraction grating duty period D2/P2. The length L2 of the second rear-end diffraction grating is equal to the length L1 of the first rear-end diffraction grating. The front-end diffraction grating period P0 is equal to the second rear-end diffraction grating period P2. The duty cycle D2/P2 of the second rear-end diffraction grating is equal to 100%. The main structure of the embodiment of FIG. 4H is substantially the same as that of the embodiment of FIG. 4G , except that the duty cycle D1/P1 of the first rear-end diffraction grating is greater than 60% and less than 100%. An improved structure of the modulated laser diode of the present invention in the embodiment of FIG. 1A or FIG. 1B can have the structure of the distributed feedback laser 1 in any of the embodiments of FIGS. 4A to 4H , thereby effectively reducing the modulation. The oscillation amplitude of the laser output power of a laser diode over time.

Please refer to FIGS. 5A to 5H , which are schematic cross-sectional views of a specific embodiment of a distributed feedback laser with an improved structure of a modulated laser diode according to the present invention. The main structure of the embodiment of FIG. 5A is substantially the same as that of the embodiment of FIG. 3A, except that the duty period D1/P1 of the first rear-end diffraction grating is greater than or equal to 40% and less than or equal to 60%. The main structure of the embodiment of FIG. 5B is substantially the same as that of the embodiment of FIG. 3C, except that the duty cycle D1/P1 of the first rear-end diffraction grating is greater than or equal to 40% and less than or equal to 60%. The main structure of the embodiment of FIG. 5C is substantially the same as that of the embodiment of FIG. 3E, except that the duty cycle D1/P1 of the first rear-end diffraction grating is greater than or equal to 40% and less than or equal to 60%. The main structure of the embodiment of FIG. 5D is substantially the same as that of the embodiment of FIG. 3G , except that the duty cycle D1/P1 of the first rear-end diffraction grating is greater than or equal to 40% and less than or equal to 60%. The main structure of the embodiment of FIG. 5E is substantially the same as that of the embodiment of FIG. 5A , except that the distributed feedback laser 1 further includes a second rear-end diffraction grating 52 . The second rear-end diffraction grating 52 is formed in the upper semiconductor layer 40 of the rear-end portion 3 of the distributed feedback laser 1 . A distance X2 between the second rear diffraction grating 52 and the active layer 30 is equal to a distance X0 between the front diffraction grating 50 and the active layer 30 . The second rear diffraction grating 52 has a second rear diffraction grating length L2. The second back-end diffraction grating 52 has a second back-end diffraction grating period P2 and a second back-end diffraction grating duty period D2/P2. The length L2 of the second rear-end diffraction grating is equal to the length L1 of the first rear-end diffraction grating. The front-end diffraction grating period P0 is equal to the second rear-end diffraction grating period P2. The duty cycle D2/P2 of the second rear-end diffraction grating is equal to 100%. The main structure of the embodiment of FIG. 5F is substantially the same as that of the embodiment of FIG. 5E , except that the first rear-end diffraction grating 51 is formed in the lower semiconductor layer 20 of the rear-end portion 3 of the distributed feedback laser 1 , And the distance X0 between the front-end diffraction grating 50 and the active layer 30 is smaller than the distance X1 between the first rear-end diffraction grating 51 and the active layer 30 . The main structure of the embodiment of FIG. 5G is substantially the same as that of the embodiment of FIG. 5C , except that the distributed feedback laser 1 further includes a second rear-end diffraction grating 52 . The second rear-end diffraction grating 52 is formed in the lower semiconductor layer 20 of the rear-end portion 3 of the distributed feedback laser 1 . A distance X2 between the second rear diffraction grating 52 and the active layer 30 is equal to a distance X0 between the front diffraction grating 50 and the active layer 30 . The second rear diffraction grating 52 has a second rear diffraction grating length L2. The second back-end diffraction grating 52 has a second back-end diffraction grating period P2 and a second back-end diffraction grating duty period D2/P2. The length L2 of the second rear-end diffraction grating is equal to the length L1 of the first rear-end diffraction grating. The front-end diffraction grating period P0 is equal to the second rear-end diffraction grating period P2. The duty cycle D2/P2 of the second rear-end diffraction grating is equal to 100%. The main structure of the embodiment of FIG. 5H is substantially the same as that of the embodiment of FIG. 5G , except that the first rear-end diffraction grating 51 is formed in the lower semiconductor layer 20 of the rear-end portion 3 of the distributed feedback laser 1 , And the distance X0 between the front-end diffraction grating 50 and the active layer 30 is smaller than the distance X1 between the first rear-end diffraction grating 51 and the active layer 30 . An improved structure of the modulated laser diode of the present invention in the embodiment of FIG. 1A or FIG. 1B can have the structure of the distributed feedback laser 1 in any of the embodiments of FIGS. 5A to 5H , thereby effectively reducing the modulation The oscillation amplitude of the laser output power of a laser diode over time.

The above are the specific embodiments of the present invention and the technical means used. According to the disclosure or teaching herein, many changes and modifications can be derived and deduced, which can still be regarded as equivalent changes made by the concept of the present invention. The effect of the invention does not exceed the substantial spirit covered by the description and drawings, and should be regarded as being within the technical scope of the present invention, and should be stated first.

Claims (20)

1. An improved structure of a modulated laser diode, characterized in that, comprising: a semiconductor substrate; and A distributed feedback laser is formed on the semiconductor substrate, wherein the distributed feedback laser is divided into a front end portion and a rear end portion, wherein the distributed feedback laser includes: A lower semiconductor layer is formed on the semiconductor substrate; an active layer formed on the lower semiconductor layer; an upper semiconductor layer formed on the active layer; A front-end diffraction grating formed in the lower semiconductor layer or in the upper semiconductor layer of the front-end portion of the distributed feedback laser, wherein the front-end diffraction grating has a front-end diffraction grating length, wherein the front-end diffraction grating having a front-end diffraction grating period and a front-end diffraction grating duty period; and A first rear diffraction grating is formed in the lower semiconductor layer or in the upper semiconductor layer at the rear end of the distributed feedback laser, wherein the first rear diffraction grating has a first rear diffraction the length of the diffraction grating, wherein the first back-end diffraction grating has a first back-end diffraction grating period and a first back-end diffraction grating duty period; The length of the front-end diffraction grating is greater than or equal to the length of the first back-end diffraction grating, wherein the period of the front-end diffraction grating is equal to the period of the first back-end diffraction grating, and the duty period of the front-end diffraction grating is greater than or equal to 40% and less than or equal to 60%, wherein the duty cycle of the first back-end diffraction grating is greater than 0% and less than 40% or greater than 60% and less than 100%. 2. The improved structure of claim 1, wherein a distance between the front-end diffraction grating and the active layer is equal to a distance between the first rear-end diffraction grating and the active layer a distance. 3 . The improved structure of a modulated laser diode as claimed in claim 2 , wherein (1) the front-end diffraction grating is formed in the lower semiconductor layer of the front-end portion of the distributed feedback laser, and the first A rear-end diffraction grating is formed in the upper semiconductor layer at the rear end of the distributed feedback laser, wherein the distributed feedback laser further includes a second rear-end diffraction grating, wherein the second rear-end diffraction grating is formed in the lower semiconductor layer of the rear end of the distributed feedback laser, or (2) the front-end diffraction grating is formed in the upper semiconductor layer of the front end of the distributed feedback laser, and the first A rear-end diffraction grating is formed in the lower semiconductor layer at the rear end of the distributed feedback laser, wherein the distributed feedback laser further includes a second rear-end diffraction grating, wherein the second rear-end diffraction grating Formed in the upper semiconductor layer of the rear end of the distributed feedback laser; wherein a distance between the second rear diffraction grating and the active layer is equal to the distance between the front diffraction grating and the active layer the distance, wherein the second back-end diffraction grating has a second back-end diffraction grating length, wherein the second back-end diffraction grating has a second back-end diffraction grating period and a second back-end diffraction grating grating duty period, wherein the second back-end diffraction grating length is equal to the first back-end diffraction grating length, wherein the front-end diffraction grating period is equal to the second back-end diffraction grating period, wherein the second back-end diffraction grating period The duty cycle of the diffraction grating is equal to 100%. 4. The improved structure of claim 1, wherein a distance between the front-end diffraction grating and the active layer is smaller than a distance between the first rear-end diffraction grating and the active layer a distance. 5 . The improved structure of a modulated laser diode as claimed in claim 4 , wherein (1) the front-end diffraction grating is formed in the upper semiconductor layer of the front-end portion of the distributed feedback laser, and the first A rear-end diffraction grating is formed in the upper semiconductor layer at the rear end of the distributed feedback laser, wherein the distributed feedback laser further includes a second rear-end diffraction grating, wherein the second rear-end diffraction grating Formed in the upper semiconductor layer of the rear end of the distributed feedback laser, and the second rear diffraction grating is located between the first rear diffraction grating and the active layer; (2) the front diffraction grating A diffraction grating is formed in the upper semiconductor layer of the front end of the distributed feedback laser, and the first rear diffraction grating is formed in the lower semiconductor layer of the rear end of the distributed feedback laser, wherein the The distributed feedback laser further includes a second rear-end diffraction grating, wherein the second rear-end diffraction grating is formed in the upper semiconductor layer at the rear end of the distributed feedback laser; (3) the front-end diffraction A grating is formed in the lower semiconductor layer of the front end of the distributed feedback laser, and the first rear diffraction grating is formed in the lower semiconductor layer of the rear end of the distributed feedback laser, wherein the distribution The distributed feedback laser further includes a second rear-end diffraction grating, wherein the second rear-end diffraction grating is formed in the lower semiconductor layer of the rear end of the distributed feedback laser, and the second rear-end diffraction grating is A grating is located between the first rear-end diffraction grating and the active layer; or (4) the front-end diffraction grating is formed in the lower semiconductor layer of the front-end portion of the distributed feedback laser, and the first rear-end A diffraction grating is formed in the upper semiconductor layer at the rear end of the distributed feedback laser, wherein the distributed feedback laser further includes a second rear diffraction grating, wherein the second rear diffraction grating is formed in In the lower semiconductor layer of the rear end of the distributed feedback laser; wherein a distance between the second rear diffraction grating and the active layer is equal to the distance between the front diffraction grating and the active layer , wherein the second back-end diffraction grating has a second back-end diffraction grating length, wherein the second back-end diffraction grating has a second back-end diffraction grating period and a second back-end diffraction grating duty service period, wherein the second back-end diffraction grating length is equal to the first back-end diffraction grating length, wherein the front-end diffraction grating period is equal to the second back-end diffraction grating period, wherein the second back-end diffraction grating period The grating duty cycle is equal to 100%. 6. The improved structure of claim 1, wherein the lower semiconductor layer is an n-type semiconductor layer. 7. The improved structure of claim 1, wherein the upper semiconductor layer is a p-type semiconductor layer. 8. The improved structure of the modulated laser diode as claimed in claim 1, wherein the modulated laser diode is a direct modulated laser diode. 9 . The improved modulated laser diode structure of claim 1 , further comprising an electro-optical absorption modulator, wherein the electro-optical absorption modulator is formed on the semiconductor substrate, wherein the The front end of the distributed feedback laser is located between the rear end of the distributed feedback laser and the electro-optical absorption modulator, wherein the modulation laser diode is an electro-optical absorption modulation laser diode. 10 . The improved structure of a modulated laser diode as claimed in claim 1 , wherein the ratio of the length of the front-end diffraction grating to the length of the first back-end diffraction grating is greater than or equal to 1 and less than 10 . or equal to 4. 11. The modulated laser diode improvement structure of any one of claims 1 to 9, wherein the duty cycle of the first rear-end diffraction grating is greater than 0% and less than or equal to 25% or greater than or equal to 75% % and less than 100%. 12 . The improved modulated laser diode structure of claim 11 , wherein the ratio of the length of the front-end diffraction grating to the length of the first back-end diffraction grating is greater than or equal to 1 and less than or equal to 4. 13 . 13. An improved structure of a modulated laser diode, characterized in that it comprises: a semiconductor substrate; and A distributed feedback laser is formed on the semiconductor substrate, wherein the distributed feedback laser is divided into a front end portion and a rear end portion, wherein the distributed feedback laser includes: A lower semiconductor layer is formed on the semiconductor substrate; an active layer formed on the lower semiconductor layer; an upper semiconductor layer formed on the active layer; A front-end diffraction grating formed in the lower semiconductor layer or in the upper semiconductor layer of the front-end portion of the distributed feedback laser, wherein the front-end diffraction grating has a front-end diffraction grating length, wherein the front-end diffraction grating having a front-end diffraction grating period and a front-end diffraction grating duty period; and A first rear diffraction grating is formed in the lower semiconductor layer or in the upper semiconductor layer at the rear end of the distributed feedback laser, wherein the first rear diffraction grating has a first rear diffraction the length of the diffraction grating, wherein the first back-end diffraction grating has a first back-end diffraction grating period and a first back-end diffraction grating duty period; The length of the front-end diffraction grating is greater than or equal to the length of the first back-end diffraction grating, wherein the period of the front-end diffraction grating is equal to the period of the first back-end diffraction grating, and the duty period of the front-end diffraction grating is greater than or equal to 40% and less than or equal to 60%, wherein a distance between the front-end diffraction grating and the active layer is smaller than a distance between the first rear-end diffraction grating and the active layer. 14. The improved structure of claim 13, wherein the duty cycle of the first rear-end diffraction grating is greater than or equal to 40% and less than or equal to 60%. 15. The improved structure of claim 14, wherein (1) the front-end diffraction grating is formed in the upper semiconductor layer of the front-end portion of the distributed feedback laser, and the first A rear-end diffraction grating is formed in the upper semiconductor layer at the rear end of the distributed feedback laser, wherein the distributed feedback laser further includes a second rear-end diffraction grating, wherein the second rear-end diffraction grating Formed in the upper semiconductor layer of the rear end of the distributed feedback laser, and the second rear diffraction grating is located between the first rear diffraction grating and the active layer; (2) the front diffraction grating A diffraction grating is formed in the upper semiconductor layer of the front end of the distributed feedback laser, and the first rear diffraction grating is formed in the lower semiconductor layer of the rear end of the distributed feedback laser, wherein the The distributed feedback laser further includes a second rear-end diffraction grating, wherein the second rear-end diffraction grating is formed in the upper semiconductor layer at the rear end of the distributed feedback laser; (3) the front-end diffraction A grating is formed in the lower semiconductor layer of the front end of the distributed feedback laser, and the first rear diffraction grating is formed in the lower semiconductor layer of the rear end of the distributed feedback laser, wherein the distribution The distributed feedback laser further includes a second rear-end diffraction grating, wherein the second rear-end diffraction grating is formed in the lower semiconductor layer of the rear end of the distributed feedback laser, and the second rear-end diffraction grating is A grating is located between the first rear-end diffraction grating and the active layer; or (4) the front-end diffraction grating is formed in the lower semiconductor layer of the front-end portion of the distributed feedback laser, and the first rear-end A diffraction grating is formed in the upper semiconductor layer at the rear end of the distributed feedback laser, wherein the distributed feedback laser further includes a second rear diffraction grating, wherein the second rear diffraction grating is formed in In the lower semiconductor layer of the rear end of the distributed feedback laser; wherein a distance between the second rear diffraction grating and the active layer is equal to the distance between the front diffraction grating and the active layer , wherein the second back-end diffraction grating has a second back-end diffraction grating length, wherein the second back-end diffraction grating has a second back-end diffraction grating period and a second back-end diffraction grating duty service period, wherein the second back-end diffraction grating length is equal to the first back-end diffraction grating length, wherein the front-end diffraction grating period is equal to the second back-end diffraction grating period, wherein the second back-end diffraction grating period The grating duty cycle is equal to 100%. 16. The improved structure of claim 13, wherein the lower semiconductor layer is an n-type semiconductor layer. 17. The improved structure of claim 13, wherein the upper semiconductor layer is a p-type semiconductor layer. 18. The improved structure of the modulated laser diode as claimed in claim 13, wherein the modulated laser diode is a direct modulated laser diode. 19. The improved structure of claim 13, further comprising an electro-optical absorption modulator, wherein the electro-optical absorption modulator is formed on the semiconductor substrate, wherein the The front end of the distributed feedback laser is located between the rear end of the distributed feedback laser and the electro-optical absorption modulator, wherein the modulation laser diode is an electro-optical absorption modulation laser diode. 20. The improved structure of a modulated laser diode as claimed in any one of claims 13 to 19, wherein the ratio of the length of the front-end diffraction grating to the length of the first back-end diffraction grating is greater than or equal to 1 and less than or equal to 4.

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