TW200814348A - Laser diode with extra optical confinement layers - Google Patents

Abstract

This invention is a laser diode with extra optical confinement layers. The laser diode has a substrate, a n-cladding layer, an under confinement unit, an active region having a multi-quantum-well to produce photons, a upper confinement unit, a p-cladding layer, and two electrodes provided electrons. The under/upper confinement unit has a refractive index layer with high refraction coefficient, and a carrier overflow suppressed layer with large energy gap. The structure of under/upper confinement unit can confine lateral optical field and compensate the shift of transverse optical field, reduce the area of whole optical field, and avoide carrier overflow effect. Finally, we get a highly optical confinement LD with an superior 10GB/sec performance.

Description

200814348 IX. DESCRIPTION OF THE INVENTION: TECHNICAL FIELD OF THE INVENTION The present invention relates to a solid state light emitting device, and more particularly to a laser diode for optical communication. [Prior Art] The transmission source for optical communication can be divided into two types: DFB laser diode (Disdbuted-feedback LD) and Fp laser diode. The DFB laser diode uses grating technology in the optical cavity. The selected specific wavelength resonance 'single-single-mode luminescence' is mainly used in high- and long-distance transmission applications, but its process is more complicated and the price is higher; *rushing laser diode is multi-longitudinal mode illumination' Because there is a larger output spectral line width =

UneWidth) '(4) In addition to the main illuminating wavelength, it is accompanied by other wavelengths with weaker intensity, so it will have a larger dispersion phenomenon in transmission, and it is suitable for short-distance and low-speed transmission applications. (4) Its production Low cost and relatively low price, so it is widely used in regional network transmission. 'See the conventional laser diode 1;|the structure of the ridge waveguide, comprising a layer substrate 11, a layer of light browning structure 2 formed on the layer substrate U, and two sheets for An electrode 12 that provides electrical energy. The tantalum substrate 11 is doped with a donor to conduct electricity. The optical limiting structure 2 has a buffer layer 21 in which a layer is connected to the layer substrate 11 to facilitate the growth of other layers, and a layer of buffer is formed from the buffer layer 2i. Layer 22 (η·—(4) 2), a lower confinement layer 23 formed on the n-type cladding layer 22, and a layer of 200814348 open onto the active layer unit 24 on the lower confinement layer 23, forming a layer An upper confinement layer 25 on the active layer unit 24, a layer formed on the upper confinement layer 25 and including a central region 261 and an etch stop layer 26 (the etching-stop iaye) surrounding the peripheral region 262 of the central region 261 :r), and a layer of p-type cladding layer 27 formed from the central region 261 upwards (卜cladding iayer) ο

Referring to FIG. 2 and FIG. 3 at the same time, the etch stop layer 26 is mainly used in the process to form a layer of the pre-defective layer by the continuation of the etching process, thereby making the laser diode P 1 I ridge waveguide The structural form; the upper and lower confinement layers 25, 23 cooperate with the η, p-type cladding layers 22, 27' and have a ridge-like structure to form a graded index separate confinement hetero-structure (GRINSCH) MU is a limited carrier and light field (〇ptical field)

"...six ball and the P-type cladding layer 27 are connected and form an ohmic contact, which can be used to inject the active layer unit 24 into the active layer unit 24 to form - having a large energy gap and a refractive index a small waveguide region, which can be used to provide the active layer unit 24

6 200814348 / plant Sacrificial carrier injection into the active layer unit 24: · Benefits, therefore requires a larger material boundary current value to provide more carrier density to cause population inversi〇n to form a laser, In particular, when the carrier is injected into the active layer unit 24, it is easier to overflow with the temperature (〇verfi〇w) phenomenon, which reduces the recombination efficiency of the carrier to the active layer unit 24. In addition, due to the optical confinement structure of the laser diode i, the refractive index is gradually limited to form a limitation of the light field, and thus the area of the laser light field distribution cannot be effectively reduced, which also makes the conventional mine The diode 1 does not reach the operating rate of l〇Gb/s. In order to meet the needs of today's fiber-optic network bandwidth, it is necessary to make a connection between the regional low-speed fiber network and the long-distance fiber-optic high-speed transmission network.

Electronic Dispersi Compensation (EDC) technology is one of the most eye-catching technologies for signal dispersion compensation. However, in the implementation of this technology, a laser source capable of directly performing high-speed modulation must be required. 'If the operating rate of the traditional lower laser diode 1 is further increased to 10 Gb/s, it will be very suitable for such transmission applications, and contribute to the development of technology. SUMMARY OF THE INVENTION It is an object of the present invention to provide a laser diode having an electronic dispersion compensation technique capable of operating at a rate of 1 〇 Gb/see and suitable for optical communication. In the invention, the laser diode having a special optical confinement structure comprises a substrate, a special optical confinement structure, and two electrodes. The special optical confinement structure is formed on the substrate, and has a first type of coating layer connected to the substrate, a layer of a lower limit unit formed on the first type of coating layer 7 200814348, and a @ JI4 a layer unit on the L<vT confined unit and having a weight of one μ & a layer formed in the active layer single-limit unit, and a layer of a second batch formed on the upper feeding unit The lower limit unit includes a layer consisting of a material having a high refractive index coefficient and connected to the first recording layer of the first layer of the film, including a Μ 古 古 古 士 士 广θ, an etch stop having a central region and a central region surrounded by a 曰' and a layer formed of a material having a high refractive index coefficient and formed on the central region, the second type of coating The layer is correspondingly connected to the glazing uncovering layer to make the laser diode have a ridge waveguide structure, and the upper and lower optical confinement layers are limited to the horizontal direction light field, and compensate the vertical field light field offset 0 pieces. An electrode is in ohmic contact with the first and second type of cladding layers respectively for Movable layer provides electrical power. The effect of the present invention is to reduce the overflow phenomenon of the carrier by using the carrier suppression layer and to reduce the distribution area of the light field by using the high refractive index material to form the upper and lower optical confinement layers, thereby improving the high frequency characteristic response of the element. Further, the above-mentioned and other technical contents, features, and effects of the present invention are described in the following detailed description of a preferred embodiment of the present invention with reference to the detailed description of the preferred embodiment of the present invention. Will be clearly presented. Before the present invention is described in detail, it is noted that in the following description, similar elements are denoted by the same reference numerals. Referring to FIG. 4, a laser diode 8 200814348 body 3 having a special optical confinement structure is a structural embodiment of a ridge waveguide, comprising a substrate 31 and a layer formed on the layer substrate 31. The special light brown limit structure 4, and the two layers of the substrate 31 are electrically doped by donor doping, in this case, a substrate made of indium (InP).

The special light uncovering structure 4 is formed by the metal organic vapor phase chemical deposition technique (m〇CVD) from the layer substrate 31, and has a layer connected to the layer substrate 31 to make the subsequent layer easy to grow. The buffer layer 41, a first type of cladding layer 42 formed by epitaxy upward from the layer of the buffer layer 41, and a lower layer of the layer 43 formed on the first layer of the layer of the layer 42, the layer is formed under the layer An active layer unit 44 on the early stage 43 is formed, an upper limit unit 45 formed on the active layer unit 4, and a second type blanket layer 46 formed on the upper limit unit 45, wherein The first and second type cladding layers 42 and 46 are respectively n-type p-cladding layers composed of a modified lining (Inp). The active layer unit 44 is made of aluminum gallium indium arsenide (A1GaInAs) and has a plurality of quantum wells composed of a plurality of compressive stress quantum wells 441 and tensile stress barriers M2 to generate photons, and the generated light field is further The upper and lower limit units 45, 43 produce the best limiting effect. The lower confinement unit 43 includes a lower optical confinement layer 431 interfacing with the first type of cladding layer 42, and a layer is formed on the lower optical confinement layer and connected by the m-layer layer 44. Carrier suppression layer. The upper threshold unit 45 includes a layer of a carrier suppression layer 451 interposed on the active layer unit 44. The layer is formed on the carrier (4) 451 and has a central region 4521 and a central region 4521 surrounded by 200814348. The etch stop layer 452 of the peripheral region 4522 and a glazing confinement layer 453 formed upward from the central region 4521.

The upper and lower optical limits | 453, 431 are respectively filled with indium gallium (InGaAsP) with a high refractive index, the thickness is between 〇〇5~〇•1, and the energy gap is between G.9eV ~1.3eV, and (4) the light field in the horizontal direction, and the continuation of the etch process can be blocked in the process by the etch stop layer 452, so that the glazing confinement layer 453 and the second type cladding layer 46 are formed to be predetermined. In this way, the laser diode 3 is in the form of a ridge waveguide, and the upper and lower optical limiting layers 453 and 431 compensate for the shift of the vertical light field. The two-layer carrier suppression layers 432 and 451 are respectively pure "(w) into a thickness of (four) to prevent carrier overflow, reduce the threshold current value of the field-polar body 3 during high-temperature operation, and enhance electrons - The recombination rate of the holes increases the resonance frequency of the laser diode 3. The sheet electrodes 32 are respectively connected to the substrate 31 and the special wire-limiting structure 4 - type cladding layer 46 and form an ohmic contact for The active layer early 44 supplies electrical energy to inject the carrier. From the laser resonance frequency and relationship, the fr

vgT d 2π

Ith where ' ^ g is the light propagation rate Γ is the overall laser triode 3 material limit factor dg / dn is the differential gain value Nw is the number of quantum wells 441 10 200814348 441 thickness dw is the width of a single quantum well)

Wact is the thickness of the active layer unit 44 (here, the ridge waveguide structure L is the length of the optical cavity. The light confinement layer 453 has a high refractive index value, so that the refractive index difference corresponding to the structure of the central region 4521 and the peripheral region 4522 can be improved. The limitation of forming a large horizontal light field is also 'the lower light confinement layer 431 can be directed to the vertical light field by the high refractive index value of the vertical light field 453, and the light field is shifted upward. , can effectively improve the limitations of the laser light field ( ^;) 'reduce the light field distribution area, and further increase the laser's resonant frequency value of 10Gb / s operation rate. See Figure 4, 81 5, and the traditional The difference in the laser diode 1 is that the laser diode 3 having the special optical confinement structure 4 of the present invention does not use "only the n, P type cladding layers 22, 27 are combined with the upper and lower confinement layers 23, 25 The formation of a refractive index gradient-limited heterostructure has a limitation on light; instead, the structure of the upper and lower confinement layers 23 25 is omitted to increase the uncovering property of the carrier and thereby lower the critical current, and to adopt a phosphorus having a high refractive index. The dowry gallstone application material consists of upper and lower limit units 4 5, 43 upper and lower light exposure limit layers 453, 431, used to reduce the distribution area of the laser light field, and at the same time, the energy barrier of the upper and lower interfaces of the active layer of the layer is higher. The sub-suppression layers 432, 451 reduce the threshold current value during high-temperature operation and increase the recombination rate of the electron-hole to increase the differential gain value' to help solve the problem of thermal effect and carrier current accumulation leading to critical current degradation. The upper and lower first brown-limit states and the 431s used in the present invention also have a refractive index grading and a heterogeneous structure, and 11 200814348 further enhances the response of the high-frequency characteristics of the 7G piece, thereby increasing the operation rate to 10 Gb/sec or more. In the above, the laser diode 3 having the special light brown limit structure 4 is mainly constructed with upper and lower optical confinement layers 453 and 431 of an indium gallium arsenide material having a high refractive index to enhance the horizontal direction. The light field is limited, and the displacement of the vertical light field is compensated. At the same time, the active layer unit 44 is constructed by using aluminum gallium arsenide material, and the indium aluminide with a larger energy gap is matched with the upper and lower interfaces.

The carrier suppression layer 432, 451 of the fragmented material has a larger conductive well depth ratio (c〇nducti〇n _ ) and a larger energy gap (indium) indium material, but Effectively suppressing the electron injection overflow phenomenon injected into the active layer unit 44, avoiding the accumulation of electrons and holes, and the thermal effect and critical current degradation caused by the step-by-step, reducing the threshold current value during the operation of the component and increasing the electrons and holes. The recombination rate, to obtain, high resonance frequency (relaxation - plus -), and then to improve the operating rate of several pieces of l 〇 Gb / sec, and is suitable for improving the old multi-mode optical fiber network to connect the new high-speed optical fiber network In the electronic dispersion compensation technology of Lu's, the creative purpose of the present invention is achieved. However, the above is only the preferred embodiment of the present invention, and the scope of the present invention cannot be limited thereto. Modifications are within the scope of the invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view showing a diagram of a band diagram illustrating the conventional laser diode of the laser diode of FIG. 1; the energy band condition of the laser diode 12 200814348 FIG. Is a refractive index profile illustrating the frequency band of the laser diode of FIG. 1; FIG. 4 is a cross-sectional view showing a preferred embodiment of the laser diode of the present invention having a special optical confinement structure; 5 is a band diagram illustrating the energy band condition of the laser diode of the present invention of FIG. 4; and FIG. 6 is a refractive index profile illustrating the frequency band of the laser diode of the present invention of FIG. 13 200814348

[Main component symbol description] 1 Laser diode 4 Special optical confinement structure 11 Substrate 41 Buffer layer 12 Electrode 42 First type cladding layer 2 Optical confinement structure 43 Lower confinement unit 21 Buffer layer 431 Lower optical confinement layer 22 η type Overlay 432 carrier suppression layer 23 lower confinement layer 44 active layer unit 24 active layer unit 441 quantum well 241 multiple quantum well 442 barrier 25 upper confinement layer 45 upper confinement unit 26 residual stop layer 451 carrier suppression layer 261 central region 452 Remaining stop layer 262 Peripheral area 4521 Central area 27 P type cladding layer 4522 Peripheral area 3 Laser diode 453 Luminescence confinement layer 31 Substrate 46 Second type cladding layer 32 Electrode 14

Claims (1)

200814348 X. Patent application scope: [•-A laser diode with a special wire structure, including a layer of substrate; ^ έ: a special braided structure' formed on the substrate and connected to the substrate a type of batch coating, a lower confinement unit on a layer of a cladding, a layer: v, a di-type batch layer formed on the lower confinement unit and having a sigma s subwell to generate photons The upper uncovering unit on the active layer unit, and the second layer are formed on the upper layer of the second layer of the coating layer, the lower confining unit comprising a layer composed of a material having a high refractive index coefficient and a lower-level confinement layer of a type of clad layer connection, the upper confinement unit comprising a (four) stop layer having a central region and a central region surrounding the central region, and the layer is composed of a material having a high refractive index coefficient and formed in the central region a glazing confinement layer, the second type of cladding layer correspondingly connected to the glazing uncovering layer to make the laser diode have a ridge waveguide structure, and the dice jdi /jg: IT» try and then 4 The upper and lower limits first limit the horizontal direction light field and compensate the vertical light field offset; and the two electrodes respectively form an ohmic contact with the first and second type cladding layers to supply electric energy to the active layer. 2. A laser diode having a special optical confinement structure according to the scope of the patent application scope, wherein the upper and the confinement units respectively have a layer connected to the upper and lower interfaces of the active layer unit and an energy gap A carrier suppression layer that is larger than the active layer cell energy gap of the layer and can suppress the overflow of the carrier. 3 · A laser diode having a special optical confinement structure according to the scope of claim 2, wherein the substrate is composed of indium phosphide, and the upper and lower 15 200814348 'light confinement layer is phosphating The indium gallium arsenide material is composed of an energy gap of 0.9 eV to 1.3 eV, and the two-layer carrier suppression layer is composed of an indium aluminide material. 4. A laser diode having a special optical confinement structure according to claim 3, wherein the thickness of the layer and the optical confinement layer is 0.05 to 0.5 // m, and the layer 2 carrier The thickness of the suppression layer is respectively 0. 0 01 〜 0 · 15 // m 〇 5. The laser diode having a special optical threshold structure according to the fourth aspect of the patent application, wherein the active layer The unit's multiple quantum wells include: • Several compression-type stress quantum wells and tensile stress barriers with an emission wavelength of 1 ·2~1 ·6 // m 〇16