Method for manufacturing double-grating semiconductor laser

Abstract

The present invention provides a method for manufacturing a dual-grating semiconductor laser, comprising: sequentially growing a first quantum well material layer, a first grating material layer, a spacer layer, and a second grating material layer on the upper surface of a substrate to form a rough outline of the laser, and dividing the laser into a distributed reflector region and a distributed feedback region; removing the second grating material layer in the distributed feedback region; manufacturing a first grating and a second grating in the distributed reflector region and the distributed feedback region, respectively; growing a cladding material on the first grating and the second grating; manufacturing a first P electrode on the cladding material in the distributed feedback region, and manufacturing a first N electrode on the lower surface of the substrate.

Description

Technical Field

[0001] The present invention relates to the field of optoelectronic devices, and in particular to a method for manufacturing a double-grating semiconductor laser. Background Art

[0002] High-power, narrow-linewidth semiconductor lasers have important applications in fiber-optic communications, free-space optical communications, and lidar. The spectral linewidth of a semiconductor laser is inversely proportional to the coupling strength of the grating; a greater grating coupling strength is more conducive to reducing the laser's linewidth.

[0003] However, a too strong grating coupling effect on the distributed feedback (DFB) laser is not conducive to the improvement of the luminous power. Therefore, it is necessary to optimize the grating parameters according to their different effects on the power and linewidth characteristics of the laser. Summary of the Invention

[0004] To address the above problems, the present invention provides a method for fabricating a dual-grating semiconductor laser, comprising: sequentially growing a first quantum well material layer, a first grating material layer, a spacer layer, and a second grating material layer on the upper surface of a first substrate to form a rough outline of the laser, and dividing the laser into a distributed reflector region and a distributed feedback region;

[0005] removing the second grating material layer in the distributed feedback region;

[0006] Manufacturing a first grating and a second grating in the distributed reflector region and the distributed feedback region respectively;

[0007] growing a cladding material on the first grating and the second grating;

[0008] A first P electrode is fabricated on the cladding material of the distributed feedback region, and a first N electrode is fabricated on the lower surface of the first substrate.

[0009] According to an embodiment of the present invention, manufacturing a first grating in the distributed reflector region includes:

[0010] The second grating material layer, the spacer layer and the first grating material layer are sequentially etched by a wet etching method to obtain the first grating.

[0011] According to an embodiment of the present invention, manufacturing a first grating in the distributed reflector region further comprises:

[0012] The second grating material layer is only etched by a wet etching method to obtain the first grating.

[0013] According to an embodiment of the present invention, manufacturing a second grating in the distributed feedback region includes:

[0014] The spacer layer and the first grating material layer are sequentially etched by a wet etching method to obtain the second grating.

[0015] According to an embodiment of the present invention, the method for manufacturing a double-grating semiconductor laser further includes:

[0016] A waveguide material layer, a second quantum well material layer, and a third grating material layer are sequentially grown on the upper surface of the second substrate to form a rough outline of the laser, and the laser is divided into a distributed reflector region and a distributed feedback region;

[0017] removing the third grating material layer and the second quantum well material layer in the distributed reflector region in sequence;

[0018] Manufacturing a third grating and a fourth grating in the distributed reflector region and the distributed feedback region respectively;

[0019] growing a cladding material on the third grating and the fourth grating until the height of the cladding material in the entire laser is at the same level;

[0020] A second P electrode is fabricated on the cladding material of the distributed feedback region, and a second N electrode is fabricated on the lower surface of the second substrate.

[0021] According to an embodiment of the present invention, manufacturing a third grating in the distributed reflector region includes:

[0022] The waveguide material layer in the distributed reflector region is etched using a wet etching method to obtain the third grating.

[0023] According to an embodiment of the present invention, manufacturing a fourth grating in the distributed feedback region includes:

[0024] The third grating material layer in the distributed feedback region is etched by a wet etching method to obtain the fourth grating.

[0025] According to an embodiment of the present invention, one or more phase-shift grating structures are introduced into the second grating and the fourth grating respectively.

[0026] According to an embodiment of the present invention, when only the second grating material layer is etched by the wet etching method to obtain the first grating, the thickness of the second grating material layer is greater than the thickness of the first grating material layer.

[0027] According to an embodiment of the present invention, the thickness of the waveguide material layer is greater than the thickness of the third grating material layer.

[0028] According to an embodiment of the present invention, a method for manufacturing a dual-grating structure is provided. This method controls the relative height of the dual-grating by etching a plurality of layers of structures, thereby making the effective refractive index of the first grating for light greater than the effective refractive index of the second grating for light, thereby causing the feedback capability of the first grating to be greater than the feedback capability of the second grating. The method provided by the present invention avoids the technical defect of the traditional method of requiring etching of quantum well active layer material to obtain a distributed reflector (DBR) light feedback region, while realizing the monolithic integration of the DBR reflector into a distributed feedback laser, thereby optimizing the power and linewidth characteristics of the laser. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The above contents and other objects, features and advantages of the present invention will become more apparent through the following description of the embodiments of the present invention with reference to the accompanying drawings, in which:

[0030] Figure 1 A flowchart schematically shows a method for manufacturing a double-grating semiconductor laser according to a first embodiment of the present invention;

[0031] Figure 2 Schematically showing some structural diagrams obtained after executing the method for manufacturing a double-grating semiconductor laser according to the first embodiment of the present invention;

[0032] Figure 3 A flowchart schematically shows a method for manufacturing a double-grating semiconductor laser according to a second embodiment of the present invention;

[0033] Figure 4 The structure diagram obtained after some steps in the manufacturing method of the double-grating semiconductor laser according to the second embodiment of the present invention are executed is shown schematically.

[0034] In the above drawings, the corresponding reference numerals are described as follows:

[0035] 11: first substrate;

[0036] 12: first quantum well material layer;

[0037] 13: first grating material layer;

[0038] 14: spacer layer;

[0039] 15: second grating material layer;

[0040] 16: first cladding material;

[0041] 17: first P electrode;

[0042] 18: first N electrode;

[0043] 21: second substrate;

[0044] 22: waveguide material layer;

[0045] 23: second quantum well material layer;

[0046] 24: third grating material layer;

[0047] 25: Second cladding material;

[0048] 26: second P electrode;

[0049] 27: second N electrode;

[0050] DBR area: distributed reflector area;

[0051] DFB area: distributed feedback area;

[0052] G1: first grating;

[0053] G2: second grating;

[0054] G3: third grating;

[0055] G4: fourth grating. DETAILED DESCRIPTION

[0056] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the detailed description below, for ease of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, it is apparent that one or more embodiments may also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessary confusion of the concepts of the present disclosure.

[0057] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise," "include," etc. used herein indicate the presence of the features, steps, operations, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, or components.

[0058] All terms used herein (including technical and scientific terms) have the meanings commonly understood by those skilled in the art unless otherwise defined. It should be noted that the terms used herein should be interpreted as having a meaning consistent with the context of this specification and should not be interpreted in an idealized or overly rigid manner.

[0059] When expressions such as "at least one of A, B and C, etc." are used, they should generally be interpreted in accordance with the meaning of the expression commonly understood by those skilled in the art (for example, "a system having at least one of A, B and C" should include but is not limited to a system having A alone, B alone, C alone, A and B, A and C, B and C, and / or A, B, C, etc.).

[0060] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

[0061] Another approach to improving the linewidth and noise characteristics of lasers is to integrate a distributed reflector (DBR) optical feedback region into the laser. This allows the laser to operate in the short-wavelength region of the DBR region's reflection spectrum (the short-wavelength direction of the reflection peak), effectively reducing the laser's linewidth and noise. However, the current process for integrating a DBR optical reflection region into a DFB laser is complex. For example, reported lasers obtain DBR reflectors by etching their quantum well active materials. This process is not conducive to achieving subsequent reliability and other indicators of the device.

[0062] Figure 1 The flowchart of the manufacturing method of the double-grating semiconductor laser according to the first embodiment of the present invention is schematically shown.

[0063] like Figure 1 As shown, the first embodiment of the present invention provides a method for manufacturing a double-grating semiconductor laser. The method may include steps S101 to S105.

[0064] In step S101, a first quantum well material layer 12, a first grating material layer 13, a spacer layer 14 and a second grating material layer 15 are sequentially grown on the upper surface of a first substrate 11 to form a rough outline of the laser, and the laser is divided into a distributed reflector (full name Distributed Bragg Reflector, abbreviated as DBR) region and a distributed feedback (full name Distributed Feedback, abbreviated as DFB) region.

[0065] In operation S102 , the second grating material layer 15 in the distributed feedback region is removed by wet etching.

[0066] According to an embodiment of the present invention, when wet etching technology is used, the spacer layer 14 material can be used as an etching stop layer material, and the etching of the second grating material layer 15 in the distributed feedback region automatically stops on the spacer layer 14 material.

[0067] In operation S103 , a wet etching method is used to form a first grating G1 and a second grating G2 in the distributed reflector region and the distributed feedback region, respectively.

[0068] According to an embodiment of the present invention, manufacturing a second grating G2 in a distributed feedback region includes:

[0069] The spacer layer 14 and the first grating material layer 13 are etched in sequence by a wet etching method to obtain the second grating G2.

[0070] According to an embodiment of the present invention, manufacturing a first grating G1 in a distributed reflector region includes:

[0071] The second grating material layer 15 , the spacer layer 14 and the first grating material layer 13 are etched in sequence by a wet etching method to obtain the first grating G1 .

[0072] At this time, the constituent materials of the first grating G1 include the materials of the second grating material layer 15, the spacer layer 14 and the first grating material layer 13, and the height of the first grating G1 can reach the sum of the thicknesses of these three layers of materials; therefore, at the same duty cycle, the optical feedback capability of the first grating G1 is greater than that of the second grating G2, thereby providing stronger beneficial feedback for the laser.

[0073] According to an embodiment of the present invention, manufacturing the first grating G1 in the distributed reflector area further includes:

[0074] By using a wet etching method, only the second grating material layer 15 is etched to obtain the first grating G1.

[0075] According to an embodiment of the present invention, when only the second grating material layer 15 is etched by wet etching to obtain the first grating G1 , the thickness of the second grating material layer 15 is greater than that of the first grating material layer 13 .

[0076] According to an embodiment of the present invention, when the materials constituting the two gratings are the same, the grating with a larger height has a stronger corresponding light feedback capability. When the heights of the two gratings are the same, the larger the band gap value of the material constituting the grating, the larger its corresponding refractive index, resulting in a stronger corresponding light feedback capability.

[0077] That is, when the first grating material layer 13 and the second grating material layer 15 are made of the same material, the height of the first grating G1 is greater than the height of the second grating G2; or

[0078] When the first grating material layer 13 and the second grating material layer 15 have the same thickness, the material bandgap of the second grating material layer 15 is larger than the material bandgap of the first grating material layer 13 , thereby ensuring that the optical feedback energy of the first grating G1 is greater than the optical feedback energy of the second grating G2 .

[0079] In operation S104 , a first cladding material 16 is grown on the first grating G1 and the second grating G2 .

[0080] In step S105 , a first P electrode 17 is formed on the cladding material of the distributed feedback region, and a first N electrode 18 is formed on the lower surface of the first substrate 11 .

[0081] Figure 2 The structure diagrams obtained after some steps in the method for manufacturing a double-grating semiconductor laser according to the first embodiment of the present invention are schematically shown.

[0082] Reference Figure 1 , Figure 2 Figure (a) represents the structure diagram obtained after step S101 is executed; Figure 2 Figure (b) represents the structure diagram obtained after step S102 is executed; Figure 2 Figure (c) represents the structure diagram obtained after step S103 is executed; Figure 2 Figure (d) represents the structural diagram obtained after steps S104 to S105 are executed.

[0083] Figure 3 The flowchart of the manufacturing method of the double-grating semiconductor laser according to the second embodiment of the present invention is schematically shown.

[0084] like Figure 3 As shown, the second embodiment of the present invention provides a method for manufacturing a double-grating semiconductor laser. The method may include steps S301 to S305.

[0085] In operation S301, a waveguide material layer 22, a second quantum well material layer 23, and a third grating material layer 24 are sequentially grown on the upper surface of the second substrate 21 to form the general outline of the laser, and the laser is divided into a distributed reflector (full name Distributed Bragg Reflector, abbreviated as DBR) region and a distributed feedback (full name Distributed Feedback, abbreviated as DFB) region.

[0086] In operation S302 , the third grating material layer 24 and the second quantum well material layer 23 in the distributed reflective mirror region are removed in sequence.

[0087] In operation S303 , a third grating G3 and a fourth grating G4 are fabricated in the distributed reflector region and the distributed feedback region, respectively.

[0088] According to an embodiment of the present invention, manufacturing the third grating G3 in the distributed reflector region includes: etching the waveguide material layer 22 in the distributed reflector region by a wet etching method to obtain the third grating G3.

[0089] According to an embodiment of the present invention, manufacturing the fourth grating G4 in the distributed feedback region includes: etching the third grating material layer 24 in the distributed feedback region by wet etching to obtain the fourth grating G4.

[0090] According to an embodiment of the present invention, when the material type constituting the third grating material layer 24 is the same as the material type of the waveguide material layer 22, the thickness of the waveguide material layer 22 is ensured to be greater than the thickness of the third grating material layer 24; or when the thickness of the waveguide material layer 22 is the same as the thickness of the third grating material layer 24, the band gap of the material constituting the waveguide material layer 22 is ensured to be greater than the band gap of the material of the third grating material layer 24, thereby ensuring that the refractive index of the waveguide material layer 22 for light is greater than the refractive index of the third grating material layer 24 for light, further ensuring that the optical feedback capability of the third grating G3 is greater than the optical feedback capability of the fourth grating G4, thereby effectively improving the linewidth characteristics of the prepared laser.

[0091] In operation S304 , a second cladding material 25 is grown on the third grating G3 and the fourth grating G4 until the height of the cladding material in the entire laser is at the same level.

[0092] In operation S305 , a second P electrode 26 is formed on the cladding material of the distributed feedback region and a second N electrode 27 is formed on the lower surface of the second substrate 21 .

[0093] According to an embodiment of the present invention, in order to improve the single longitudinal mode yield of laser light emission, one or more phase-shift grating structures are introduced into the second grating G2 and the fourth grating G4 respectively.

[0094] According to an embodiment of the present invention, by changing the period of the gratings in the distributed reflector region and the distributed feedback region, the operating wavelength of the laser (determined by the grating in the DFB region) is located in the short wavelength direction of the reflection peak of the DBR light reflection spectrum, thereby reducing the spectral linewidth of the device.

[0095] Figure 4 The structure diagram obtained after some steps in the manufacturing method of the double-grating semiconductor laser according to the second embodiment of the present invention are executed is shown schematically.

[0096] Reference Figure 3 , Figure 4 Figure (a) represents the structure diagram obtained after step S301 is executed; Figure 4 Figure (b) represents the structure diagram obtained after step S302 is executed; Figure 4 Figure (c) represents the structural diagram obtained after steps S303 to S305 are executed.

[0097] In the third embodiment of the present invention, based on the first embodiment, after growing the first cladding material 16, the first contact layer material is continued to be grown; in order to reduce the current diffusion to the distributed reflector area, the first contact layer material in the distributed reflector area is subsequently removed by a wet etching method; a third P electrode is made on the first contact layer material in the distributed feedback area, and the rest of the manufacturing process is the same as that of the first embodiment.

[0098] In the fourth embodiment of the present invention, based on the second embodiment, after growing the second cladding material 25, the second contact layer material is continued to be grown; in order to reduce the current diffusion to the distributed reflector area, the second contact layer material in the distributed reflector area is subsequently removed by a wet etching method; a fourth P electrode is made on the second contact layer material in the distributed feedback area, and the rest of the manufacturing process is the same as that of the second embodiment.

[0099] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for manufacturing a double-grating semiconductor laser, comprising: Growing a first quantum well material layer, a first grating material layer, a spacer layer, and a second grating material layer in sequence on the upper surface of the first substrate to form a rough outline of the laser, and dividing the laser into a distributed reflector region and a distributed feedback region; removing the second grating material layer in the distributed feedback region; Manufacturing a first grating and a second grating in the distributed reflector region and the distributed feedback region respectively; growing a cladding material on the first grating and the second grating; A first P electrode is fabricated on the cladding material of the distributed feedback region, and a second N electrode is fabricated on the lower surface of the first substrate.

2. The method according to claim 1, wherein Producing a first grating in the distributed reflector region includes: The second grating material layer, the spacer layer and the first grating material layer are sequentially etched by a wet etching method to obtain the first grating.

3. The method according to claim 1, wherein The first grating is produced in the distributed reflector region, further comprising: Only the second grating material layer is etched by a wet etching method to obtain the first grating.

4. The method according to claim 3, wherein: In the case where only the second grating material layer is etched by the wet etching method to obtain the first grating, the thickness of the second grating material layer is greater than the thickness of the first grating material layer.

5. The method according to claim 1, wherein Producing a second grating in the distributed feedback region comprises: The spacer layer and the first grating material layer are sequentially etched by a wet etching method to obtain the second grating.

6. The method according to claim 5, wherein: One or more phase-shifting grating structures are introduced into the second grating.

7. A method for manufacturing a double-grating semiconductor laser, comprising: Growing a waveguide material layer, a second quantum well material layer, and a third grating material layer in sequence on the upper surface of the second substrate to form a rough outline of the laser, and dividing the laser into a distributed reflector region and a distributed feedback region; removing the third grating material layer and the second quantum well material layer in the distributed reflector region in sequence; Manufacturing a third grating and a fourth grating in the distributed reflector region and the distributed feedback region respectively; growing a cladding material on the third grating and the fourth grating until the height of the cladding material in the entire laser is at the same level; A second P electrode is fabricated on the cladding material of the distributed feedback region, and a second N electrode is fabricated on the lower surface of the second substrate.

8. The method according to claim 7, wherein: Producing a third grating in the distributed reflector region includes: The waveguide material layer in the distributed reflector region is etched using a wet etching method to obtain the third grating.

9. The method according to claim 7, wherein: Producing a fourth grating in the distributed feedback region includes: The third grating material layer in the distributed feedback region is etched by a wet etching method to obtain the fourth grating.

10. The method according to claim 9, wherein: One or more phase-shifting grating structures are introduced into the fourth grating.

11. The method according to claim 7, wherein: The thickness of the waveguide material layer is greater than the thickness of the third grating material layer.

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