Dual grating semiconductor laser

Abstract

The application provides a double-grating semiconductor laser, which comprises a distributed reflector region and a distributed feedback region. The distributed reflector region comprises a first N electrode formed on the lower surface of a first substrate, the first substrate, a first quantum well material layer formed on the upper surface of the first substrate, a first grating formed on the first quantum well material layer, and a first cladding material layer formed on the first grating. The distributed feedback region comprises a second N electrode formed on the lower surface of a second substrate, the second substrate, a second quantum well material layer formed on the upper surface of the second substrate, a second grating formed on the second quantum well material layer, a second cladding material layer formed on the second grating, and a first P electrode formed on the second cladding material layer. The height of the first grating is greater than the height of the second grating, and the height of the second grating is 5-200 nm.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optoelectronic devices, in particular to a double-grating semiconductor laser. BACKGROUND

[0002] Semiconductor laser based on InP material is an important light source device in optical communication system, which has the advantages of small size, low power consumption, easy integration and modulation. In order to avoid serious dispersion and other problems in the transmission process, the laser for communication should have good single mode characteristics.

[0003] Introducing distributed feedback grating structure in the laser is an important means to obtain single mode semiconductor. However, in the traditional distributed feedback laser, single grating cannot produce single mode and real-time monitoring of single mode at the same time, so that the single mode laser cannot be stably output in the laser device, resulting in unstable spectral linewidth of the laser. SUMMARY

[0004] In view of the above problems, the present application provides a double-grating semiconductor laser, comprising:

[0005] The distributed reflector region is suitable for reflecting light incident on the distributed reflector region, comprising:

[0006] The first N electrode is formed on the lower surface of the first substrate.

[0007] The first substrate;

[0008] The first quantum well material layer is formed on the upper surface of the first substrate.

[0009] The first grating is formed on the first quantum well material layer.

[0010] The first cladding material is formed on the first grating.

[0011] The distributed feedback region is suitable for mode selection of light reflected by the distributed reflector region, realizing single mode light emission, comprising:

[0012] The second N electrode is formed on the lower surface of the second substrate.

[0013] The second substrate;

[0014] The second quantum well material layer is formed on the upper surface of the second substrate.

[0015] The second grating is formed on the second quantum well material layer.

[0016] The second cladding material is formed on the second grating.

[0017] The first P electrode is formed on the second cladding material.

[0018] wherein the height of the first grating is greater than the height of the second grating, and the height of the second grating is 5-200 nm.

[0019] According to an embodiment of the present application, the first grating comprises:

[0020] a first grating material layer formed on the first quantum well material layer;

[0021] a first spacer layer formed on the first grating material layer;

[0022] a second grating material layer formed on the first spacer layer.

[0023] According to an embodiment of the present application, the second grating comprises:

[0024] a third grating material layer formed on the second quantum well material layer.

[0025] According to an embodiment of the present application, the double-grating semiconductor laser further comprises:

[0026] a distributed reflector region adapted to reflect light incident on the distributed reflector region, comprising:

[0027] a third N-electrode formed on the lower surface of the third substrate;

[0028] the third substrate;

[0029] a third grating formed on the upper surface of the third substrate;

[0030] a third cladding material formed on the third grating;

[0031] a distributed feedback region adapted to mode select the light reflected by the distributed reflector region to achieve single mode light emission, comprising:

[0032] a fourth N-electrode formed on the lower surface of the fourth substrate;

[0033] the fourth substrate;

[0034] a waveguide material layer formed on the upper surface of the fourth substrate;

[0035] a third quantum well material layer formed on the waveguide material layer;

[0036] a fourth grating formed on the third quantum well material layer;

[0037] a fourth cladding material formed on the fourth grating;

[0038] a second P-electrode formed on the fourth cladding material.

[0039] According to the embodiment of the present application, the material type and thickness of the third grating are the same as the material type and thickness of the waveguide material layer, and the thickness is 100-1000 nm; the fourth grating comprises a fourth grating material layer.

[0040] According to the embodiment of the present application, the first N electrode is the same as the second N electrode, the third N electrode and the fourth N electrode;

[0041] The first substrate is the same as the second substrate, the third substrate and the fourth substrate;

[0042] The material type and thickness of the first quantum well material layer, the second quantum well material layer and the third quantum well material layer are the same, and each comprises one of InGaAsP material and InGaAlAs material;

[0043] The material type of the first cladding material, the second cladding material, the third cladding material and the fourth cladding material is the same, and is suitable for providing restriction on light and electricity in the laser;

[0044] The first P electrode is the same as the second P electrode;

[0045] The material type and thickness of the first grating material layer, the third grating material layer and the fourth grating material layer are the same.

[0046] According to the embodiment of the present application, the thickness of the first cladding material and the second cladding material is the same, and is 500-2500 nm;

[0047] The thickness of the third cladding material and the fourth cladding material is different, but the top of the third cladding material is flush with the top of the fourth cladding material, and the thickness of the third cladding material and the fourth cladding material is 500-2500 nm;

[0048] The thickness of the first grating material layer, the third grating material layer and the fourth grating material layer is 5-200 nm;

[0049] The thickness of the second grating material layer is 10-300 nm;

[0050] The thickness of the first spacer layer is 10 nm.

[0051] According to the embodiment of the present application, the first quantum well material layer, the second quantum well material layer and the third quantum well material layer each comprise one or more quantum wells, and are suitable for being used as gain material for generating laser; wherein the plurality of quantum wells have the same structure.

[0052] According to the embodiment of the present application, one or more phase shift grating structures are introduced in the above-mentioned second grating and fourth grating structures respectively; wherein the above-mentioned phase shift grating structures are the same.

[0053] According to the embodiment of the present application, the above-mentioned distributed feedback region further comprises:

[0054] A first contact layer material is formed between the above-mentioned second cladding material and the first P electrode;

[0055] A second contact layer material is formed between the above-mentioned fourth cladding material and the second P electrode;

[0056] Wherein the material type and thickness of the above-mentioned first contact layer material and second contact layer material are the same, and the thickness is 50-500nm.

[0057] According to the embodiment of the present application, the double grating semiconductor laser provided by the present application introduces a double grating structure, and the height of the grating of the distributed reflector region is greater than the height of the grating of the optical feedback region, so that the feedback ability of the grating of the distributed reflector region to light is greater than the feedback ability of the grating of the optical feedback region to light, which makes the single mode laser output in the laser device more stable, and the spectral line width of the laser is more stable. BRIEF DESCRIPTION OF DRAWINGS

[0058] The above content and other purposes, features and advantages of the present application will be more apparent through the following description of the embodiments of the present application with reference to the accompanying drawings, in which:

[0059] Figure 1 is a schematic diagram of a double grating semiconductor laser provided by the first embodiment of the present application;

[0060] Figure 2 is a schematic diagram of a double grating semiconductor laser provided by the second embodiment of the present application.

[0061] In the above-mentioned drawings, the corresponding reference signs are explained as follows:

[0062] 11: first N electrode;

[0063] 12: first substrate;

[0064] 13: first quantum well material layer;

[0065] 14: first cladding material;

[0066] 21: second N electrode;

[0067] 22: second substrate;

[0068] 23: second quantum well material layer;

[0069] 24: second cladding material;

[0070] 25: first P electrode;

[0071] 31: third N electrode;

[0072] 32: third substrate;

[0073] 33: third cladding material;

[0074] 41: fourth N electrode;

[0075] 42: fourth substrate;

[0076] 43: waveguide material layer;

[0077] 44: third quantum well material layer;

[0078] 45: fourth cladding material;

[0079] 46: second P electrode;

[0080] DBR: distributed Bragg reflector region;

[0081] DFB: distributed feedback region;

[0082] G1: first grating;

[0083] G2: second grating;

[0084] G3: third grating;

[0085] G4: fourth grating. DETAILED DESCRIPTION

[0086] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the following detailed description of the embodiments of the present disclosure, numerous specific details are set forth in order to provide a thorough understanding of the embodiments of the present disclosure. However, it would be apparent to those skilled in the art that the embodiments of the present disclosure can be practiced without these specific details. In other instances, well-known structures and functions have been omitted to avoid unnecessarily complicating the present disclosure with details that would be apparent to those skilled in the art.

[0087] The terms used herein are merely used to describe specific embodiments and are not intended to limit the present disclosure. The terms "include", "comprise" and the like used herein indicate the presence of the described features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0088] All terms used herein, including technical and scientific terms, have the meanings commonly understood by one of ordinary skill in the art unless otherwise defined. It should be noted that the use of any terms herein should not be interpreted as excluding the use of any other terms that are equivalent in meaning to those terms.

[0089] In the case of using expressions similar to "at least one of A, B, and C, etc.", it is generally interpreted to include any of them alone, any combination of at least two of them, and the like unless otherwise defined.

[0090] In order to make the objectives, technical solutions, and advantages of the present application clearer, the following further describes the present application in conjunction with specific embodiments and with reference to the accompanying drawings.

[0091] The first embodiment of the present application provides a double-grating semiconductor laser, comprising: a distributed reflector region (English full name: Distributed Bragg Reflector, abbreviated as DBR region) and a distributed feedback region (English full name: Distributed Feedback, abbreviated as DFB region). The distributed reflector region is adapted to reflect light incident to the distributed reflector region; the distributed feedback region is adapted to mode select the light reflected by the distributed reflector region, to realize single-mode light emission. The distributed reflector region comprises: a first N electrode 11 formed on the lower surface of a first substrate 12; the first substrate 12; a first quantum well material layer 13 formed on the upper surface of the first substrate 12; a first grating G1 formed on the first quantum well material layer 13; a first cladding material 14 formed on the first grating G1; the distributed feedback region comprises: a second N electrode 21 formed on the lower surface of a second substrate 22; the second substrate 22; a second quantum well material layer 23 formed on the upper surface of the second substrate 22; a second grating G2 formed on the second quantum well material layer 23; a second cladding material 24 formed on the second grating G2; a first P electrode 25 formed on the second cladding material 24; wherein the height of the first grating G1 is greater than the height of the second grating G2, and the height of the second grating G2 is 5-200 nm.

[0092] According to the embodiment of the present application, the double-grating semiconductor laser has the height of the first grating G1 greater than the height of the second grating G2, resulting in the feedback capability of the first grating G1 greater than the feedback capability of the second grating G2, thereby effectively improving the linewidth characteristics of the prepared laser.

[0093] According to the embodiment of the present application, the second grating G2 comprises: a third grating material layer formed on the second quantum well material layer 23.

[0094] According to the embodiment of the present application, the first grating G1 comprises: a first grating material layer formed on the first quantum well material layer 13; a first interval layer formed on the first grating material layer; and a second grating material layer formed on the first interval layer.

[0095] According to the embodiment of the present application, the first grating G1 can further comprise: only the second grating material layer; in this case, it is necessary to ensure that the thickness of the second grating material layer is greater than the thickness of the third grating material layer.

[0096] According to the embodiment of the present application, the first grating G1 is equivalent to a light reflector, which reflects the laser light incident on the distributed reflector region back to the distributed feedback region, thereby reducing the spectral line width of the laser; the second grating G2 performs the mode selection function of the distributed feedback region, thereby realizing the single longitudinal mode operation of the laser; and finally, under the joint action of the two gratings, the line width characteristics of the device can be effectively improved.

[0097] The second embodiment of the present application further provides a double-grating semiconductor laser, which comprises: a distributed reflector region (DBR region in English) and a distributed feedback region (DFB region in English). The distributed reflector region comprises: a third N electrode 31 formed on the lower surface of a third substrate 32; the third substrate 32; a third grating G3 formed on the upper surface of the third substrate 32; and a third cladding material layer 33 formed on the third grating G3. The distributed feedback region comprises: a fourth N electrode 41 formed on the lower surface of a fourth substrate 42; the fourth substrate 42; a waveguide material layer 43 formed on the upper surface of the fourth substrate 42; a third quantum well material layer 44 formed on the waveguide material layer 43; a fourth grating G4 formed on the third quantum well material layer 44; a fourth cladding material layer 45 formed on the fourth grating G4; and a second P electrode 46 formed on the fourth cladding material layer 45.

[0098] According to the embodiment of the present application, the material type and thickness of the third grating G3 are the same as the material type and thickness of the waveguide material layer 43, which are InGaAsP material and 100-1000 nm in thickness; and the fourth grating G4 comprises a fourth grating material layer.

[0099] According to the embodiment of the present application, the third grating G3 is equivalent to a light reflector, which reflects the laser incident to the distributed reflector region back to the distributed feedback region, thereby reducing the spectral line width of the laser; the fourth grating G4 performs the mode selection function of the distributed feedback region, thereby realizing the single longitudinal mode operation of the laser; and the thickness of the waveguide material layer 43 is greater than the thickness of the fourth grating material layer, so that the grating coupling strength of the distributed reflector region is greater than the grating coupling strength of the distributed feedback region, and finally under the joint action of the gratings in the two regions, the line width characteristics of the device can be effectively improved.

[0100] According to the embodiment of the present application, the first N electrode 11 is the same as the second N electrode 21, the third N electrode 31 and the fourth N electrode 41; the first substrate 12 is the same as the second substrate 22, the third substrate 32 and the fourth substrate 42, and is an InP substrate; the material types and thicknesses of the first quantum well material layer 13 and the second quantum well material layer 23 and the third quantum well material layer 44 are the same, and all include one of InGaAsP material and InGaAlAs material; the material types of the first cladding material 14 and the second cladding material 24, the third cladding material 33 and the fourth cladding material 45 are the same, and all are InP cladding materials, which are suitable for providing the restriction on the light and electricity in the laser; the first P electrode 25 is the same as the second P electrode 46; the material types and thicknesses of the first grating material layer, the third grating material layer and the fourth grating material layer are the same; and the material type of the first spacing layer is InP.

[0101] According to the embodiment of the present application, preferably, the materials of the first grating material layer, the second grating material layer, the third grating material layer and the fourth grating material layer are InGaAsP, in which case, only the sum of the thicknesses of the layers constituting the first grating G1 is greater than the sum of the thicknesses of the layers constituting the second grating G2, or the sum of the thicknesses of the layers constituting the third grating G3 is greater than the sum of the thicknesses of the layers constituting the fourth grating G4, so that the line width characteristics of the prepared laser can be effectively improved.

[0102] According to the embodiment of the present application, the thicknesses of the first cladding material 14 and the second cladding material 24 are the same, and are 500-2500 nm; the thicknesses of the third cladding material 33 and the fourth cladding material 45 are different, but the top of the third cladding material 33 is flush with the top of the fourth cladding material 45, wherein the thicknesses of the third cladding material 33 and the fourth cladding material 45 are both 500-2500 nm; the thicknesses of the first grating material layer, the third grating material layer and the fourth grating material layer are all 5-200 nm; the thickness of the second grating material layer is all 10-300 nm; and the thickness of the first spacing layer is 10 nm.

[0103] According to the embodiment of the present application, the first quantum well material layer 13, the second quantum well material layer 23 and the third quantum well material layer 44 each include one or more quantum wells, which are suitable for being used as gain material for generating laser; wherein the quantum wells are of the same structure.

[0104] According to the embodiment of the present application, one or more phase shift grating structures are introduced in the second grating G2 and the fourth grating G4 respectively; wherein the phase shift grating structures are of the same structure.

[0105] According to the embodiment of the present application, the distributed feedback region further includes: a first contact layer formed between the second cladding material 24 and the first P electrode 25; a second contact layer formed between the fourth cladding material 45 and the second P electrode 46; wherein the material type and thickness of the first contact layer and the second contact layer are the same, and each is an InGaAs contact layer with a thickness of 50-500nm.

[0106] The third embodiment of the present application has the same structure as the first embodiment, and only has the first InGaAs contact layer added at the relevant position of the distributed feedback region; the fourth embodiment of the present application has the same structure as the second embodiment, and only has the second InGaAs contact layer added at the relevant position of the distributed feedback region.

[0107] The above-described specific embodiments further explain the purpose, technical solutions and advantages of the present application, and it should be understood that the above-described specific embodiments are only for the specific embodiments of the present application, and are not used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A dual-grating semiconductor laser, comprising: a distributed reflector region adapted to reflect light incident to the distributed reflector region, comprising: a first N-electrode formed on a lower surface of a first substrate; the first substrate, a material of the first substrate comprising InP; a first quantum well material layer formed on an upper surface of the first substrate; a first grating formed on the first quantum well material layer, reflecting laser light incident to the distributed reflector region back to a distributed feedback region; wherein the first grating comprises: a first grating material layer formed on the first quantum well material layer; a first spacer layer formed on the first grating material layer; and a second grating material layer formed on the first spacer layer; a first cladding material formed on the first grating, adapted to provide confinement of light and electricity in the laser; the distributed feedback region adapted to mode select light reflected by the distributed reflector region, achieving single mode light emission, comprising: a second N-electrode formed on a lower surface of a second substrate; the second substrate, a material of the second substrate comprising InP; a second quantum well material layer formed on an upper surface of the second substrate; a second grating formed on the second quantum well material layer, performing a mode selection function of the distributed feedback region; wherein the second grating comprises: a third grating material layer formed on the second quantum well material layer; a second cladding material formed on the second grating, adapted to provide confinement of light and electricity in the laser; a first P-electrode formed on the second cladding material; wherein a height of the first grating is greater than a height of the second grating, and the height of the second grating is 5-200 nm.

2. The laser of claim 1, wherein, the first N-electrode is the same as the second N-electrode; a material type and thickness of the first quantum well material layer and the second quantum well material layer are the same, and both comprise one of InGaAsP material and InGaAlAs material; a material type of the first cladding material and the second cladding material is the same; a material type and thickness of the first grating material layer and the third grating material layer are the same. 3.The laser of claim 1, wherein: a thickness of the first cladding material and the second cladding material is the same, and both are 500-2500 nm; a thickness of the first grating material layer and the third grating material layer is 5-200 nm; a thickness of the second grating material layer is 10-300 nm; a thickness of the first spacer layer is 10 nm.

4. The laser of claim 1, wherein, the first quantum well material layer and the second quantum well material layer each comprise one or more quantum wells, and are adapted to serve as gain material for generating laser light; wherein the plurality of quantum wells are of the same structure.

5. The laser of claim 1, wherein, one or more phase shift grating structures are introduced in the second grating structure respectively; wherein the plurality of phase shift grating structures are the same.

6. The laser of claim 1, wherein, the distributed feedback region further comprises: a first contact layer material formed between the second cladding material and the first P-electrode; wherein a thickness of the first contact layer is 50-500 nm.

7. A dual-grating semiconductor laser, comprising: a distributed reflector region adapted to reflect light incident on the distributed reflector region, comprising: a third N-electrode formed on a lower surface of a third substrate; the third substrate, a material of the third substrate comprising InP; a third grating formed on an upper surface of the third substrate, reflecting laser light incident on the distributed reflector region back to the distributed feedback region; a third cladding material formed on the third grating, adapted to provide confinement of light and current in the laser; the distributed feedback region adapted to mode select light reflected by the distributed reflector region, enabling single mode lasing, comprising: a fourth N-electrode formed on a lower surface of a fourth substrate; the fourth substrate, a material of the fourth substrate comprising InP; a waveguide material layer formed on an upper surface of the fourth substrate; a third quantum well material layer formed on the waveguide material layer; a fourth grating formed on the third quantum well material layer, performing the mode selection function of the distributed feedback region; wherein the fourth grating comprises a fourth grating material layer; a fourth cladding material formed on the fourth grating, adapted to provide confinement of light and current in the laser; wherein the third cladding material and the fourth cladding material have different thicknesses, but the top of the third cladding material is level with the top of the fourth cladding material; a second P-electrode formed on the fourth cladding material; wherein the third grating has a height greater than the height of the fourth grating; the material and thickness of the third grating are the same as the material and thickness of the waveguide material layer, and both have a thickness of 100-1000 nm.

8. The laser of claim 7, wherein: the third N-electrode and the fourth N-electrode are the same; a material of the third quantum well material layer comprises one of InGaAsP material and InGaAlAs material; the third cladding material and the fourth cladding material are the same in material type.

9. The laser of claim 7, wherein: the third cladding material and the fourth cladding material both have a thickness of 500-2500 nm; the fourth grating material layer both has a thickness of 5-200 nm.

10. The laser of claim 7, wherein, the third quantum well material layer both comprises one or more quantum wells, adapted to serve as gain material for generating laser light; wherein the plurality of quantum well structures are the same.

11. The laser of claim 7, wherein: one or more phase-shift grating structures are introduced in the fourth grating structure respectively; wherein the plurality of phase-shift grating structures are the same.

12. The laser of claim 7, wherein, the distributed feedback region further comprises: a second contact layer material formed between the fourth cladding material and the second P-electrode; wherein the second contact layer has a thickness of 50-500 nm.

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