TWI534490B - Light transmitting device and light transceiver module - Google Patents

Description

Optical transmission device and optical transmission module

The present invention relates to an optical communication device, and more particularly to an optical transmission device and an optical transmission module.

The fiber optical communication module is composed of a fiber optical transceiver module and a circuit module, wherein the fiber transmission module usually includes an optical transmission device (light Transmitting device) and a light receiving device. Optical fiber communication has the advantages of fast transmission speed, high capacity, low distortion, etc., and can effectively cope with the signal transmission of large-scale high-resolution images in the future. Optical fiber communication can be applied to long-distance signal transmission, such as submarine optical fiber cable, and can also be applied to short-distance local side signal transmission. Since the bandwidth of optical fiber communication is hundreds of times more than that of traditional cable communication, and the technology of optical fiber communication is still breaking through, the future of optical fiber network still has considerable growth, so some people say that the 21st century is the century of light.

In order to further increase the signal transmission capacity of the optical fiber, Wavelength Division Multiplex (WDM) technology is often used to enable multiple optical signals having different wavelengths to be simultaneously transmitted in one optical fiber to improve the overall information transmission amount. However, once the number of wavelengths increases, the width of each wavelength and the spacing of the center wavelength, the overall optical power, the cross-talk, and the maximum range over which the fiber can be transmitted must be considered. The most commonly used techniques for making a split-wave multiplexer are: (1) Thin Film Filter (TFF), (2) Array Waveguide Grating (AWG), and (3) Fiber Bragg (Fiber Bragg) Grating, FBG). Due to the above-mentioned split-wave multiplexer, the transmission distance is limited, and the working wavelength of the optical signal is mostly between 1475 and 1625 nm, so as to increase the transmittance of light and reduce transmission loss, but the relative cost is also relatively low. High, can not be mass produced in a low-cost semiconductor process.

In addition, in the spectroscopic technique, a known technique is used to fabricate a concave grating on the Rowland circle, so that the diffracted light generated by the incident light source is focused on the Loren circle to improve the conventional planar grating. (planar grating) requires two concave mirrors to make the light focus space and improve the grating splitting efficiency. In addition, the concave grating combines the functions of grating spectroscopic and concave mirror imaging. If the incident light source contains many different wavelengths of optical signals, the reflected light waves will reflect the different wavelengths of the optical signals to different angles due to the interference. The effect of splitting, which in turn reduces energy loss, and the space it takes up, replaces the traditional large monochromator.

The present invention relates to an optical transmission device and an optical transmission module using the same, which focuses light signals of different wavelengths to a preset by a reflection type diffraction grating or other types of reflective surfaces. At the output point, an output signal for collecting the optical signals is obtained. Since the reflective diffraction grating is a light collecting component fabricated by a semiconductor process technology, it has the advantages of low insertion loss, low crosstalk, and easy mass production, and thus the channel number and bandwith of the optical transmission device can be Increase and significantly reduce the cost of production.

According to an aspect of the invention, an optical transmission apparatus is provided which includes a plurality of emitters, a first reflection type diffraction grating, and an output portion. The transmitters are used to emit a plurality of optical signals of different wavelengths. The first reflective diffraction grating faces the emitters. The first reflective diffraction grating includes a first curved profile and a plurality of first diffraction structures. The first curved surface profile has a plurality of first contour points. The first diffraction structures are disposed on the first curved surface contour to focus the optical signals of different wavelengths on a predetermined output point. The first diffraction structure is disposed between the first contour points by a plurality of first grating pitches, and at least some of the first grating pitches are different from each other. In addition, the output has an inlet. The inlet is configured on the preset output point to obtain an output signal of the plurality of optical signals.

According to an aspect of the invention, an optical transmission apparatus is provided which includes a plurality of emitters, a reflection type condensing mirror, and an output portion. The transmitters are used to emit a plurality of optical signals of different wavelengths. Reflective concentrating mirrors face these emitters. The reflective concentrating mirror includes a concave surface for focusing optical signals of different wavelengths onto a predetermined output point. In addition, the output has an inlet. The inlet is configured on the preset output point to obtain an output signal of the plurality of optical signals.

According to an aspect of the invention, an optical transmission module is provided which includes an optical transmission device and a light receiving device. The light receiving device is configured to receive an output signal output by the output portion of the optical transmission device.

In order to better understand the above and other aspects of the present invention, the preferred embodiments are described below, and in conjunction with the drawings, the detailed description is as follows:

The optical transmission module of this embodiment includes an optical transmission device and a light receiving device. The light receiving device separates and focuses the optical signals of different wavelengths onto a predetermined output surface by using a reflective diffraction grating. The reflective diffraction grating combines the functions of splitting and focusing, thus replacing the collimator and focusing lens in traditional optical systems, thereby reducing the number of components used in optical systems and complex alignment problems. . In addition, the optical transmission device uses another reflective diffraction grating or other type of reflective condenser to focus different wavelengths of optical signals on a predetermined output point to obtain an output signal of the optical signals.

Please refer to FIG. 1 , which illustrates a schematic diagram of an optical transmission module according to an embodiment. The optical transmission module 1 includes a light receiving device 10 and an optical transmission device 20. The optical transmission device includes a plurality of emitters 22, a first reflective diffraction grating 24, and an output portion 26. The transmitters 22 are configured to emit a plurality of optical signals L1 L Ln of different wavelengths. A reflective diffraction grating faces the emitters 22. The first reflective diffraction grating 24 includes a first curved profile 242 and a plurality of first diffraction structures 244 (see the structure of FIG. 3). The first curved surface contour 242 has a plurality of first contour points P ₀ ~ Pn (see the structure of FIG. 3). The first diffraction structures 244 are disposed on the first curved surface contour 242 for focusing the optical signals L1 LLn of different wavelengths on a predetermined output point. The first diffraction structure 244 is disposed between the first contour points with a plurality of first grating pitches, and at least some of the first grating pitches are different from each other (see the structure of FIG. 3). In addition, the output portion 26 has an inlet 262 disposed at a predetermined output point to obtain an output signal L for collecting the optical signals.

Further, the light receiving device 10 includes an input portion 12, a second reflective diffraction grating 14, and a plurality of receiving portions 16. The input unit 12 is configured to input a plurality of optical signals L1 to Ln of different wavelengths. The second reflective diffraction grating 14 is located at one of the outlets 121 of the input portion 12. The second reflective diffraction grating 14 includes a second curved profile 142 and a plurality of second diffraction structures 144 (see the structure of FIG. 3). The second curved surface contour 142 has a plurality of second contour points P ₀ to Pn (see the structure of FIG. 3). The second diffraction structures 144 are disposed on the second curved surface contour 142 for separating the optical signals L1 L Ln of different wavelengths and focusing the optical signals on a predetermined output surface 162 . The second diffraction structures 144 are disposed between the contour points P ₀ -Pn with a plurality of second grating pitches. At least some of the second grating pitches are different from each other. In addition, the plurality of receiving portions 16 are disposed on the preset output surface 162 for receiving the separated optical signals L1 L Ln of different wavelengths.

In the above, the first reflection type diffraction grating 24 has a function of collecting light, and the second reflection type diffraction grating 14 has a function of splitting light. The working principle of concentrating and splitting is reversible, the only difference being that the positions of the transmitting end and the receiving end are exactly opposite, so whether the optical signals L1 LLn of different wavelengths are emitted from the plurality of transmitters 22 or from the plurality of receiving parts 16 Receiving optical signals L1~Ln of different wavelengths is to collect optical signals or separate optical signals by the principle of diffraction. Only the portion of the second reflection type diffraction grating 14 will be described below, and the portion of the first reflection type diffraction grating 24 can be known by reverse pushing, and therefore the description will not be repeated.

Please refer to FIG. 1 , FIG. 2 and FIG. 3 simultaneously. FIG. 2 is a schematic diagram showing a diffraction principle of a second reflective diffraction grating, and FIG. 3 is a schematic diagram of a reflective diffraction grating according to an embodiment. schematic diagram. For convenience of description, the shape of the diffraction structure 144 illustrated in FIG. 3 is illustrated by a similar triangle. The diffraction structure 144 is disposed between the contour points P ₀ to Pn at a plurality of grating pitches. At least some of the grating pitches are different from each other such that the optical signals L1 L Ln of different wavelengths are directed to the preset output surface 162 in a manner substantially perpendicular to the preset output surface 162 . The number of mutually different grating pitches can be adjusted according to the actual design. For convenience of explanation, FIG. 3 only illustrates three different grating spacings d ₀ , d ₁ and d ₂ . In one embodiment, the grating pitches d ₀ , d _{1 ,} and d ₂ are the lengths of the line segments from the contour points P ₀ to P ₁ , P ₁ to P ₂ , and P ₂ to P ₃ , respectively.

In Figures 2 and 3, the central contour point P ₀ is the center point of the curved contour 142, and the reference point (preferably the contour point P ₁ ) is the next contour point temporarily selected during the optical simulation and adjustment process, when a single When the wavelength ray is emitted from a known incident angle α to a region grating with a line segment length d ₀ connecting P ₀ and P ₁ as a grating pitch, the focus position on the preset output surface 162 after diffraction may be combined with The ideal focus has an aberration Δy' (aberration). The aberration Δy' can be passed through the following grating equation (Grating Equation)

Sinα+sinβ= Abbreviated induced spectral resolution Δ λ _A = .

Wherein, the grating pitch d ₀ is the grating pitch of the regional grating P ₁ P ₀ ; the diffraction angle β is the angle of the assumed single-wavelength ray A1 after being circulated by the regional grating P ₁ P ₀ , which is a function of λ; It is the wavelength of A1; m is the diffraction order; the distance of the diffracted ray whose distance r' is A1 is diffracted by the area grating P ₁ P ₀ to the preset output surface 162. Under the premise that the grating spacing d ₀ , the diffraction angle β, the wavelength λ, the diffraction order m and the distance r′ are known, the value of each aberration Δy′ can be solved by the grating formula to find the corresponding aberration analysis. Degree Δ λ _A . Thus, the position of the contour point on the curved contour 142 of the second reflective diffraction grating 14 can be adjusted from the central contour point P ₀ as a reference point, and the grating spacing and the local grating profile of the region are repeatedly adjusted by optical simulation. Find a position point where the aberration resolution Δ A _{A is} less than a predetermined value as the position of the preferred second contour point P ₁ , and then start from the contour point P ₁ as a reference point, and adjust the grating pitch repeatedly by the same optical simulation. The grating profile of the region is found to be a position where the aberration resolution Δ λ _{A is} smaller than a predetermined value as the position of the contour point P ₂ which is preferably one more, and thus repeated until the curved contour 142 of the second reflection type diffraction grating 14 The second reflective diffraction grating 14 thus obtained will be a preferred grating which can be obtained by optical simulation, until the outline of the grating of the region with different grating pitches is full. Similarly, it can be inferred that the first reflective diffraction grating 24 is also a preferred grating which can be obtained by optical simulation.

Compared with the conventional concave grating with a fixed grating pitch, it is almost impossible to form a vertical or nearly vertical intersection between the diffracted light and the focused circular arc on the Roland circle, which is not practical. In contrast, the present invention finds the non-fixed grating pitch and the non-circular surface curved contour 142 by optical simulation, so that the diffracted light can be directed to the preset output surface 162 substantially perpendicular to the preset output surface 162. Not only the diffraction efficiency is better, but the preset output surface 162 does not have to be an arc on the Roland circle which is difficult to implement, but may be another output surface that is easy to implement, such as a straight line on a plane, such a second The reflective diffraction grating 14 will be of very high value in practical applications. Similarly, it can be inferred that the transmitter 22 can also be arranged in a straight line on a plane to improve the utility.

In addition, the second reflective diffraction grating 14 has a non-planar curved contour 142 (for example, a three-dimensional spherical surface or a curved surface) and unequal grating pitches, and is conventionally engraved on a flat metal or glass surface with a precision diamond knife. The method of making the diffractive structure 144 becomes unsuitable for at least the reason that the diamond knife is difficult to change the pitch and the surface of the non-planar material is difficult to operate. Therefore, the second reflective diffraction grating 14 is more suitable for the process. The material is selected by using a semiconductor substrate material (such as germanium or III-V semiconductor material) to etch a non-planar diffraction structure 144 on the vertical surface of the wafer by etching, and then from the wafer. Cut it out. Similarly, it can be inferred that the first reflective diffraction grating 24 can also be fabricated using the above process.

In an embodiment, the receiving portion 16 is, for example, a photoelectric converter composed of a group of photoelectric elements, such as photodiodes, which are sequentially arranged in parallel on the preset output surface 162 to different wavelengths. The optical signals L1~Ln are converted into a set of electrical signals. At least some of the spacings between the receiving portions 16 are different from each other, and the position of the receiving portion 16 is related to the grating spacing setting, and can be adjusted according to the actual design, so that the receiving portions 16 are non-equally arranged on the preset output surface. 162. The number of receiving sections 16 is not limited, and the looking-up input section 12 may allow transmission of the maximum number of optical signals. In addition, the receiving portion 16 can also be a set of optical fibers or a hybrid receiver in which optical fibers and optoelectronic components are combined. After each optical fiber is divided into optical signals of a single wavelength, data processing is performed by the subsequent photoelectric components, but the optical signals of the single wavelength can be directly transmitted again without photoelectric conversion.

In addition, the emitter 22 is composed, for example, of a set of variable wavelength laser diodes having a variable wavelength range of, for example, between 600 nm and 800 nm. When the number of the transmitters 22 is larger, and the frequency band that the center wavelength of each of the optical signals L1 to Ln can tolerate is smaller, the number of optical signals L1 to Ln that can be transmitted is also higher, and the number thereof is at least three or more. The output portion 26 is, for example, an optical fiber having an inlet 262 at its end that is located at a predetermined output point. The optical signals L1~Ln of different wavelengths can be incident into the inside of the optical fiber through the inlet 262 and simultaneously transmitted inside the optical fiber without mutual interference, so that the signal transmission amount and the bandwidth are relatively increased.

In an embodiment, the input portion 12 is, for example, an optical fiber having an outlet 121 at its end. The input unit and the output unit 26 may be connected by the same optical fiber or different optical fibers, so that the optical signals L1 to Ln of different wavelengths can be transmitted from the output unit 26 of the optical transmission device 20 to the input unit 12 of the light receiving device 10. If the resolution of the light receiving device 10 to the optical signals L1 to Ln is higher, the number of available frequency bands is also higher. For example, when the available bandwidth is 200 nm and the minimum resolution is 5 nanometers (nm), one fiber can simultaneously transmit 40 different wavelengths of optical signals L1~Ln. If the transmission speed is 10 Gbps, the amount of data that can be transmitted in one second is about 400 Gb, which is equivalent to the capacity of a Blu-ray disc. Therefore, replacing the traditional cable with an optical fiber can overcome the limitation of the conventional cable bandwidth and reduce the noise interference of the electromagnetic wave. Therefore, the optical transmission device 1 of the present invention can be applied to a module using an optical fiber as a transmission interface, for example, a fiber transmission module connected between a computer and its peripheral electronic devices, or a connection server in a regional network. The optical fiber transmission module between the printer, the photocopier and the terminal computer, to greatly increase the amount of data transmitted.

Next, please refer to FIGS. 4A-4D, which are schematic diagrams showing optical transmission devices of four different types of embodiments. Different from the above embodiments, each embodiment focuses the optical signals L1 LLn on a predetermined output point by using different types of reflective concentrating mirrors, and then transmits the optical signals to the light receiving device 10 via an output portion 26 . The input portion 12 is for the purpose of optical transmission. In FIG. 4A, the reflective concentrating mirror 30 has a concave surface 301, for example, a continuous curved surface, so that the optical signals L1 LLn of different wavelengths are refracted via the concave surface 301 and then focused on a predetermined output point. In FIG. 4B, the reflective concentrating mirror has a concave surface 302, for example, composed of a set of non-continuous step faces 31, so that the optical signals L1 LLn of different wavelengths are refracted through the respective step faces 31 and then focused on a preset. At the output point. Further, in FIG. 4C, the reflection type condensing mirror 32 is, for example, an elliptical mirror or a spherical mirror having a concave surface 303 and a focal point P. The preset output point is located at the focus P such that the parallel incident optical signals L1~Ln can be refracted via the concave surface 303 and then focused on the focus P. In Fig. 4D, the reflective concentrating mirror 33 is, for example, a parabolic mirror having a concave surface 304 and a focal point P. The preset output point is located at the focus P such that the parallel incident optical signals L1~Ln can be refracted via the concave surface 304 and then focused on the focus.

Next, please refer to FIG. 5 and FIG. 6. FIG. 5 is an exploded perspective view of the light receiving device according to an embodiment, and FIG. 6 is a schematic view showing the light traveling in the optical channel of FIG. 5. In order to obtain a better quality optical signal, the light receiving device 10 further includes an upper waveguide plate 120, a lower waveguide plate 130, a first extinction element 150 and a second extinction element 160.

The lower waveguide plate 130 is disposed substantially parallel to the upper waveguide plate 120. The upper waveguide plate 120 has a first reflective surface 122, and the lower waveguide plate 130 has a second reflective surface 132 opposite the first reflective surface 122. The optical path 140 is formed between the first reflecting surface 122 and the second reflecting surface 132, so that the optical signals L1 to Ln from the input portion 12 travel in the optical channel 140 as shown in FIG. The optical channel 140 formed between the first reflective surface 122 and the second reflective surface 132 is generally of a cavity type, which is different from the principle of total reflection used for transmitting light in the optical fiber. In this embodiment, the optical signals L1~Ln are limited. Reflectively reflected between these reflective surfaces and forwarded, but can also be filled with appropriate media (such as glass, plastic, or acrylic) for the light signal to be reflected and forwarded while preventing dust or other pollution. The matter accumulates on the upper and lower waveguide plates to affect the flatness and reflectivity of the waveguide plate.

The upper waveguide plate 120 and the lower waveguide plate 130 must have good flatness and reflectivity, so that the optical signals L1 to Ln can achieve the lowest loss and the best when traveling between the upper waveguide plate 120 and the lower waveguide plate 130. The light source concentrates the effect. Therefore, the material of the upper waveguide plate 120 and the lower waveguide plate 130 is, for example, stainless steel, tantalum wafer, glass, optical disk or hard disk. In addition, if the material reflectance of the upper waveguide plate 120 and the lower waveguide plate 130 is less than the required standard, a high-reflection film may be disposed on the first reflective surface 122 and the second reflective surface 132 to solve the problem. Preferably, the material of the highly reflective film is an aluminum film.

In order to prevent oxidation, rust, roughness, etc. of the surfaces of the first reflective surface 122 and the second reflective surface 132 over time, the flatness and reflectivity of the surface of the reflective surface are reduced, and the first reflective surface 122 and the second reflective surface are A first protective film and a second protective film (not shown) are respectively disposed on the high reflective film of the surface 132. The material of the protective film is, for example, cerium oxide.

The light receiving device disclosed in the above embodiments of the present invention regulates the optical signals of different wavelengths input from the input unit to travel in the optical channel between the upper and lower waveguide plates, so that the optical signals are more concentrated and less likely to diverge. In combination with the jagged extinction element, the optical signal with too large incident angle is eliminated, thereby reducing the stray light reaching the receiving portion, so that the optical signal to be separated is not interfered by stray light, so as to obtain clearer signal quality. .

In conclusion, the present invention has been disclosed in the above preferred embodiments, and is not intended to limit the present invention. A person skilled in the art can make various changes and modifications without departing from the spirit and scope of the invention. Therefore, the scope of the invention is defined by the scope of the appended claims.

1. . . Optical transmission module

10. . . Light receiving device

12. . . Input section

14. . . Second reflective diffraction grating

16. . . Receiving department

20. . . Optical transmission device

twenty two. . . launcher

twenty four. . . First reflective diffraction grating

26. . . Output department

30, 32, 33. . . Reflective condenser

31. . . Step surface

L1~Ln. . . Optical signal

L. . . Output signal

121. . . Export

142. . . Second surface contour

144. . . Diffractive structure

P ₀ ~Pn. . . Outline point

162. . . Preset output face

d ₀ , d ₁ , d ₂ . . . Grating spacing

120. . . Upper waveguide plate

130. . . Lower waveguide plate

122. . . First reflecting surface

132. . . Second reflecting surface

140. . . Optical channel

150. . . First extinction element

160. . . Second extinction element

242. . . First surface contour

262. . . Entrance (preset output point)

301, 302, 303, 304. . . Concave surface

P. . . focus

FIG. 1 is a schematic diagram of an optical transmission module according to an embodiment.

FIG. 2 is a schematic diagram showing the diffraction principle of the second reflective diffraction grating.

FIG. 3 is a schematic diagram of a reflective diffraction grating according to an embodiment.

4A-4D are schematic views showing optical transmission devices of four different types of embodiments.

FIG. 5 is an exploded perspective view of a light receiving device according to an embodiment.

Figure 6 is a schematic diagram showing the travel of light in the optical channel of Figure 5.

1. . . Optical transmission module

10. . . Light receiving device

12. . . Input section

14. . . Second reflective diffraction grating

16. . . Receiving department

20. . . Optical transmission device

twenty two. . . launcher

twenty four. . . First reflective diffraction grating

26. . . Output department

121. . . Export

142. . . Second surface contour

162. . . Preset output face

242. . . First surface contour

262. . . Entrance (preset output point)

L1~Ln. . . Optical signal

L. . . Output signal

Claims (12)

An optical transmission device comprising: a plurality of transmitters for transmitting a plurality of optical signals of different wavelengths; a first reflective diffraction grating facing the emitters, the first reflective diffraction gratings comprising: a first a curved surface contour having a plurality of first contour points; and a plurality of first diffraction structures disposed on the first curved surface contour for focusing the optical signals of different wavelengths on a predetermined output point, The first diffraction structure is disposed between the first contour points by a plurality of first grating pitches, at least a portion of the first grating pitches are different from each other; and an output portion having an inlet, the inlet The preset output point is configured to obtain an output signal of the plurality of optical signals. An optical transmission device comprising: a plurality of transmitters for transmitting a plurality of optical signals of different wavelengths; and a reflective concentrating mirror facing the emitters, the reflective concentrating mirrors comprising a concave surface for the different wavelengths The optical signal is focused on a preset output point; and an output portion has an inlet, and the inlet is disposed on the preset output point to obtain an output signal for collecting the optical signals. The optical transmission device of claim 2, wherein the concave surface is a continuous curved surface or is composed of a set of non-continuous step surfaces. The optical transmission device of claim 2, wherein the reflective concentrating mirror is a parabolic mirror, an elliptical mirror or a spherical mirror. An optical transmission module comprising: the optical transmission device according to claim 1; and a light receiving device for receiving the output signal output by the output portion of the optical transmission device. An optical transmission module comprising: the optical transmission device according to claim 2; and a light receiving device for receiving the output signal output by the output portion of the optical transmission device. The optical transceiver module of claim 5, wherein the light receiving device comprises: an input portion for inputting the optical signals of different wavelengths; and a second reflective diffraction grating located at An output of the second reflection type diffraction grating includes: a second curved surface profile having a plurality of second contour points; and a plurality of second diffraction structures disposed on the second curved surface contour Separating the optical signals of the different wavelengths and focusing on a predetermined output surface, wherein the second diffraction structures are disposed between the second contour points by a plurality of second grating pitches, at least some of the The second gratings are different from each other; and the plurality of receiving portions are disposed on the predetermined output surface for receiving the separated optical signals of the different wavelengths. The optical transceiver module of claim 7, wherein the light receiving device further comprises: an upper waveguide plate having a first reflecting surface; and a lower waveguide plate substantially parallel to the upper waveguide plate And have a second reflective surface, the first reflective surface is opposite to the second reflective surface, and an optical path is formed between the first reflective surface and the second reflective surface to enable the optical signals from the input portion Traveling within the optical channel. The optical transceiver module of claim 8, wherein the light receiving device further comprises a first matting component and a second extinction component, respectively disposed on opposite sides of the optical channel. The optical transmission module of claim 5, wherein the transmitters comprise a set of variable wavelength laser diodes. The optical transmission module of claim 5 or 6, wherein the output portion comprises an optical fiber. The optical transmission module of claim 7, wherein the spacing between at least some of the receiving portions is different from each other.