Structure and method of fabrication of an electroabsorption modulated laser chip

Abstract

The application relates to the technical field of lasers, and provides a structure and a manufacturing method of an electro-absorption modulation laser chip. The electro-absorption modulation laser chip is composed of a laser region 1, an isolation region 2 and a modulation region 3 which are coupled in sequence, and specifically, the laser region 1, the isolation region 2 and the modulation region 3 have respective ridge waveguide structures; wherein the quantum well width under the ridge waveguide structure of the modulation region 3 is larger than the quantum well width under the ridge waveguide structure of the laser region 1 by a preset value. In the application, the ridge waveguide process is adopted, the growth of an iron-doped buried layer is not needed, the failure phenomenon caused by the epitaxial steps and the iron-doped buried growth is reduced, and the application has the advantages of high yield and low cost.

Description

[Technical Field]

[0001] This invention relates to the field of laser technology, and in particular to the structure and manufacturing method of an electroabsorption modulated laser chip. [Background Technology]

[0002] Since its inception, optical fiber communication has developed rapidly in just 30 years. The rapid growth of backend demands such as cloud computing, big data, and smartphones has placed increasingly higher requirements on chip transmission rates and distances. High speed and low power consumption have become a trend in the future development of optoelectronic chips. Currently, in applications with speeds of 25Gb / s and below, direct-modulated lasers are widely used in optical communication transmission due to their advantages of fewer epitaxial steps and lower cost. However, with the increase in transmission rate and the extension of transmission distance, distributed feedback direct-modulated lasers (DFB) are limited in transmission rate and bandwidth due to their capacitance limitations. Electro-absorption modulated lasers (EML), with their small capacitance, compensate for the shortcomings of direct-modulated lasers in this regard and are more advantageous at speeds of 56Gb / s and higher.

[0003] Currently, high-speed electroabsorption modulated lasers commonly employ buried layer structures for epitaxial growth and chip fabrication. The typical process involves laser epitaxial growth – grating fabrication – grating burial – modulator region etching – modulator region docking growth – iron-doped buried layer growth – ohmic contact layer epitaxial growth – P-electrode fabrication – N-electrode fabrication. This approach is characterized by complex epitaxial growth processes, requiring multiple epitaxial growth steps, resulting in high costs. Particularly in the iron-doped buried material growth, the process is difficult to control, and iron-zinc diffusion is prone to occur, leading to power saturation, reduced bandwidth, and other issues, resulting in low overall yield and high chip cost.

[0004] Therefore, overcoming the shortcomings of the existing technology is an urgent problem to be solved in this technical field. [Summary of the Invention]

[0005] The technical problem to be solved by the embodiments of the present invention is that the existing epitaxial growth process is complex, requires multiple epitaxial growths, and is costly. In particular, the process is difficult to control in the growth of iron-doped buried materials. Iron-zinc diffusion is prone to occur during growth, which leads to power saturation, reduced bandwidth and other phenomena in the chip, resulting in a low overall yield and high chip cost.

[0006] The embodiments of the present invention adopt the following technical solutions:

[0007] In a first aspect, the present invention provides a structure for an electro-absorption modulated laser chip, comprising a laser region 1, an isolation region 2, and a modulation region 3 sequentially coupled to form an electro-absorption modulated laser chip, specifically:

[0008] The laser region 1, isolation region 2 and modulation region 3 each have their own ridge waveguide structure;

[0009] The quantum well width in the ridge waveguide structure of modulation region 3 is larger than the quantum well width in the ridge waveguide structure of laser region 1 by a preset value.

[0010] Preferably, the laser region includes an N-type InP substrate 11, a modulation region quantum well 12, a laser quantum well 13, a grating layer 14, a P-type InP cladding layer 15, a BCB insulating resin 16, an InGaAs contact layer 17, and a SiO2 insulating layer 18, specifically:

[0011] A laser quantum well 13 is grown on an N-type InP substrate 11 under a ridge waveguide structure. Modulation region quantum wells 12 are grown on both sides of the laser quantum well 13. A grating layer 14 is fabricated on the laser quantum well 13.

[0012] The groove structure on both sides of the spine structure on the grating layer 14 is filled with SiO2 insulating layer 18, wherein the middle region of the SiO2 insulating layer 18 is filled with BCB insulating resin 16; the P-type InP cladding layer 15 constitutes the spine structure on the grating layer 14 and the two outer walls of the groove structure.

[0013] The InGaAs contact layer 17 is grown on the ridge waveguide for electrical connection with the metal electrode layer 19.

[0014] The quantum well under the ridge waveguide structure of the laser region 1 is the laser quantum well 13.

[0015] Preferably, the modulation region includes an N-type InP substrate 31; a modulation region quantum well 32, a P-type InP cladding layer 35, a BCB insulating resin 36, an InGaAs contact layer 37, and a SiO2 insulating layer 38, specifically:

[0016] A modulation region quantum well 32 is grown on an N-type InP substrate 31. The modulation region quantum well 32 is etched with a preset width under a ridge waveguide structure, which is the width of the quantum well under the ridge waveguide structure of the modulation region 3.

[0017] The SiO2 insulating layer 38 is filled in the etched modulation region quantum well position and double trench structure, and the SiO2 insulating layer 38 is filled with BCB insulating resin 36.

[0018] The P-type InP cladding 35 forms the spine structure on the modulation region quantum well 32 and the two outer walls of the channel structure.

[0019] The InGaAs contact layer 37 is grown on the ridge waveguide for electrical connection with the metal electrode layer 39.

[0020] Preferably, the isolation region includes an N-type InP substrate 21; a modulation region quantum well 22; a P-type InP cladding layer 25; a BCB insulating resin 26; an InGaAs contact layer 27; and a SiO2 insulating layer 28, specifically:

[0021] A modulation region quantum well 22 is grown on an N-type InP substrate 21, and the modulation region quantum well 22 is etched with a predetermined width under a ridge waveguide structure.

[0022] The SiO2 insulating layer 28 is filled in the etched modulation region quantum well 22 and the double trench structure, and the SiO2 insulating layer 28 is filled with BCB insulating resin 26.

[0023] The P-type InP cladding 25 forms the spine structure on the modulation region quantum well 22 and the two outer walls on the channel structure.

[0024] Preferably, when the width of the laser quantum well 13 under the ridge waveguide structure of the laser region 1 is 18 μm, the width of the modulation region quantum well 32 under the ridge waveguide structure of the modulation region 3 is 25 μm.

[0025] Preferred options also include:

[0026] In the ridge waveguide structure of laser region 1, the width of the ridge structure is 2.2 μm, and the width of the double grooves on both sides of the ridge structure is 16 μm respectively.

[0027] The width of the spinal structure in modulation zone 3 is 4 μm, and the width of the double grooves on both sides of the spinal structure is 120 μm each.

[0028] Preferably, the length of the laser region 1 is 320 μm, the length of the isolation region 2 is 50 μm, and the length of the modulation region 3 is 160 μm.

[0029] Preferably, in the region 15 μm away from the light-emitting surface of the modulation region 3, the corresponding position of the BCB insulating resin is etched away, leaving the SiO2 insulating layer 18 covering the sidewall of the ridge structure and the surface of its dual-channel structure.

[0030] Preferably, in the adjacent electroabsorption modulated laser chips on the wafer, the first electroabsorption modulated laser chip and the second electroabsorption modulated laser chip that are adjacent to each other are formed by connecting the laser region of the first electroabsorption modulated laser chip with the modulation region of the second electroabsorption modulated laser chip.

[0031] The first and third electroabsorption modulated laser chips, which are adjacent to each other, are formed by P-type InP claddings that each contain a laser region, an isolation region, and a modulation region.

[0032] In a second aspect, the present invention provides a method for manufacturing an electro-absorption modulated laser chip, comprising fabricating the structure of the electro-absorption modulated laser chip as described in the first aspect through growth and etching processes.

[0033] Compared with the prior art, the beneficial effects of the embodiments of the present invention are as follows:

[0034] This invention employs a ridge waveguide process, eliminating the need for iron-doped buried layer growth, thus reducing the failures caused by epitaxial steps and iron-doped buried growth. It offers advantages such as high yield and low cost. [Attached Image Description]

[0035] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0036] Figure 1 This is a schematic diagram of a ridge waveguide structure for an electroabsorption modulated laser chip provided in an embodiment of the present invention;

[0037] Figure 2 This is a schematic diagram of the structure of an electroabsorption modulated laser chip provided in an embodiment of the present invention;

[0038] Figure 3 This is a schematic diagram of the laser region cross-sectional structure in an electroabsorption modulated laser chip provided in an embodiment of the present invention;

[0039] Figure 4 This is a schematic diagram of the laser region structure dimensions of an electroabsorption modulated laser chip provided in an embodiment of the present invention;

[0040] Figure 5 This is a schematic cross-sectional view of the modulation region of an electroabsorption modulation laser chip provided in an embodiment of the present invention;

[0041] Figure 6 This is a schematic diagram of the modulation region structure dimensions of an electroabsorption modulation laser chip provided in an embodiment of the present invention;

[0042] Figure 7 This is a cross-sectional schematic diagram of the isolation region structure of an electroabsorption modulated laser chip provided in an embodiment of the present invention;

[0043] Figure 8 This is a cross-sectional view of the light-emitting surface of the modulation region of an electroabsorption modulated laser chip provided in an embodiment of the present invention.

Detailed Implementation Methods

[0044] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0045] In the description of this invention, the terms "inner", "outer", "longitudinal", "lateral", "upper", "lower", "top", "bottom", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and do not require that this invention must be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0046] Furthermore, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0047] Example 1:

[0048] Embodiment 1 of the present invention provides a structure for an electroabsorption modulated laser chip, as follows: Figure 1 As shown, the electro-absorption modulated laser chip consists of laser region 1, isolation region 2, and modulation region 3, which are sequentially coupled together. Specifically:

[0049] The laser region 1, isolation region 2 and modulation region 3 each have their own ridge waveguide structure;

[0050] The quantum well width in the ridge waveguide structure of modulation region 3 is larger than the quantum well width in the ridge waveguide structure of laser region 1 by a preset value.

[0051] The preset value is determined by matching the width of the quantum well in laser region 1 and the size of the quantum well in modulation region 3. If it is smaller than the preset value, the modulator region 3 at the junction will not be able to absorb all the photons emitted by laser region 1. If the preset value is set too wide, it will affect the size of parasitic capacitance and junction capacitance. Therefore, the preset value is obtained based on debugging experience.

[0052] The quantum well width is in Figure 1 The corresponding quantum well width difference characteristics are not directly shown in the text; please refer to [reference needed]. Figure 3 and Figure 5 Or compare Figure 4 and Figure 6 To understand, among them, Figure 3 It corresponds Figure 2 The complete electroabsorption modulated laser chip shown is a cross-sectional view of its laser region C-C'. Figure 5 It corresponds Figure 2 The complete electroabsorption modulated laser chip shown is a cross-sectional view of its modulation region B-B'. Figure 4 It is the corresponding Figure 3 A diagram showing the key structural layer dimensions in a specific embodiment. Figure 6 It is the corresponding Figure 5 A diagram showing the key structural layer dimensions in a specific embodiment.

[0053] In this embodiment of the invention, the use of ridge waveguide technology eliminates the need for iron-doped buried layer growth, reducing the failures caused by epitaxial steps and iron-doped buried growth, and offering advantages such as high yield and low cost.

[0054] like Figure 3 As shown, based on an embodiment of the present invention, the laser region includes an N-type InP substrate 11, a modulation region quantum well 12, a laser quantum well 13, a grating layer 14, a P-type InP cladding layer 15, a BCB insulating resin 16, an InGaAs contact layer 17, and a SiO2 insulating layer 18. Specifically:

[0055] A laser quantum well 13 is grown on an N-type InP substrate 11 under a ridge waveguide structure. Modulation region quantum wells 12 are grown on both sides of the laser quantum well 13. A grating layer 14 is fabricated on the laser quantum well 13.

[0056] The groove structure on both sides of the spine structure on the grating layer 14 is filled with SiO2 insulating layer 18, wherein the middle region of the SiO2 insulating layer 18 is filled with BCB insulating resin 16; the P-type InP cladding layer 15 constitutes the spine structure on the grating layer 14 and the two outer walls of the groove structure.

[0057] The InGaAs contact layer 17 is grown on the ridge waveguide for electrical connection with the metal electrode layer 19.

[0058] like Figure 5 As shown, based on an embodiment of the present invention, the modulation region includes an N-type InP substrate 31; a modulation region quantum well 32, a P-type InP cladding layer 35, a BCB insulating resin 36, an InGaAs contact layer 37, and a SiO2 insulating layer 38, specifically:

[0059] A modulation region quantum well 32 is grown on an N-type InP substrate 31, and the modulation region quantum well 32 is etched with a predetermined width under a ridge waveguide structure.

[0060] The SiO2 insulating layer 38 is filled in the etched modulation region quantum well position and double trench structure, and the SiO2 insulating layer 38 is filled with BCB insulating resin 36.

[0061] The P-type InP cladding 35 forms the spine structure on the modulation region quantum well 32 and the two outer walls of the channel structure.

[0062] The InGaAs contact layer 37 is grown on the ridge waveguide for electrical connection with the metal electrode layer 39.

[0063] like Figure 7 As shown Figure 2 The cross-sectional view of D-D' is based on an embodiment of the present invention. The isolation region includes an N-type InP substrate 21; a modulation region quantum well 22; a P-type InP cladding layer 25; a BCB insulating resin 26; an InGaAs contact layer 27; and a SiO2 insulating layer 28. Specifically:

[0064] A modulation region quantum well 22 is grown on an N-type InP substrate 21, and the modulation region quantum well 22 is etched with a predetermined width under a ridge waveguide structure.

[0065] The SiO2 insulating layer 28 is filled in the etched modulation region quantum well position and double trench structure, and the SiO2 insulating layer 28 is filled with BCB insulating resin 26.

[0066] The P-type InP cladding 25 forms the spine structure on the modulation region quantum well 22 and the two outer walls on the channel structure.

[0067] like Figure 4 and Figure 6 As shown, when the width of the laser quantum well 13 under the ridge waveguide structure of the laser region 1 is 18 μm, the width of the modulation region quantum well 32 under the ridge waveguide structure of the modulation region 3 is 25 μm.

[0068] like Figure 4 and Figure 6 As shown, as a full-size demonstration, the corresponding structural dimensions of the laser region and modulation region also include:

[0069] In the ridge waveguide structure of laser region 1, the width of the ridge structure is 2.2 μm, and the width of the double grooves on both sides of the ridge structure is 16 μm each; in modulation region 3, the width of the ridge structure is 4 μm, and the width of the double grooves on both sides of the ridge structure is 120 μm. The length of the laser region is 320 μm, the length of the isolation region is 50 μm, and the length of the modulation region is 160 μm.

[0070] In this embodiment of the invention, considering the precision of the cleaving and dicing equipment, and to ensure the consistency of the cleaved end faces, the invention also proposes an improved solution, such as... Figure 8 As shown Figure 2In the cross-sectional view along line A-A', in the region 15 μm from the light-emitting surface of modulation region 3, the corresponding position of the BCB insulating resin is etched away, leaving a SiO2 insulating layer 18 covering the sidewall of the ridge structure and the surface of its dual-channel structure. In this embodiment of the invention, the BCB filling is to reduce the parasitic capacitance at the modulator end. If BCB is present in this region, the BCB material is soft, and pulling will occur during the cleaving process, resulting in protruding areas on the end face, which will affect the subsequent coating process.

[0071] As for the scenario setting where the BCB insulating resin at the corresponding position is etched away in the region 15µm away from the light-emitting surface of the modulation region 3, the specific context is as follows: In the adjacent electro-absorption modulated laser chips on the wafer, the first electro-absorption modulated laser chip and the second electro-absorption modulated laser chip that are adjacent to each other are formed by the laser region of the first electro-absorption modulated laser chip and the modulation region of the second electro-absorption modulated laser chip being adjacent to each other; the first electro-absorption modulated laser chip and the third electro-absorption modulated laser chip that are adjacent to each other are formed by the P-type InP cladding layer in their respective laser region, isolation region and modulation region being adjacent to each other.

[0072] The terms "first," "second," and "third" here have no special limiting meaning. They are used only to facilitate the description of different individuals within a class of objects. They should not be interpreted as having a special limiting meaning in terms of order or other aspects.

[0073] Example 2

[0074] This invention also provides a method for manufacturing an electroabsorption modulated laser chip, comprising fabricating the structure of the electroabsorption modulated laser chip described in Example 1 through growth and etching processes.

[0075] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A structure for an electroabsorption modulated laser chip, characterized in that, The electro-absorption modulated laser chip consists of a laser region (1), an isolation region (2), and a modulation region (3) coupled sequentially. Specifically: The laser region (1), isolation region (2) and modulation region (3) each have their own ridge waveguide structure; Among them, the quantum well width under the ridge waveguide structure in the modulation region (3) is larger than the quantum well width under the ridge waveguide structure in the laser region (1) by a preset value; In the laser region (1), a laser quantum well (13) is grown on an N-type InP substrate (11) under a ridge waveguide structure. Modulation region quantum wells (12) are grown on both sides of the laser quantum well (13). A grating layer (14) is fabricated on the laser quantum well (13). The channel structure on both sides of the spine structure on the grating layer (14) is filled with a SiO2 insulating layer (18), wherein the middle region of the SiO2 insulating layer (18) is filled with BCB insulating resin (16). A P-type InP cladding layer (15) constitutes the spine structure on the grating layer (14) and the two outer sidewalls of the channel structure. An InGaAs contact layer (17) is grown on the ridge waveguide for electrical connection with the metal electrode layer (19). The quantum well under the ridge waveguide structure of the laser region (1) is the laser quantum well (13). The preset value is matched with the width of the quantum well of the laser region (1) and the size of the quantum well of the modulation region (3). Its purpose is to ensure that the modulator region (3) at the docking point can absorb all photons emitted by the laser region (1) and reduce the influence of parasitic capacitance and junction capacitance.

2. The structure of the electroabsorption modulated laser chip according to claim 1, characterized in that, Modulation region 3 includes an N-type InP substrate (31); a modulation region quantum well (32), a P-type InP cladding (35), a BCB insulating resin (36), an InGaAs contact layer (37), and a SiO2 insulating layer (38), specifically: A modulation region quantum well (32) is grown on an N-type InP substrate (31). The modulation region quantum well (32) is etched with a preset width under a ridge waveguide structure, which is the width of the quantum well under the ridge waveguide structure of the modulation region (3). The SiO2 insulating layer (38) is filled in the etched modulation region quantum well position and double trench structure, and the SiO2 insulating layer (38) is filled with BCB insulating resin (36). The P-type InP cladding (35) forms the spine structure on the modulation region quantum well (32) and the two outer walls on the channel structure; The InGaAs contact layer (37) is grown on the ridge waveguide for electrical connection with the metal electrode layer (39).

3. The structure of the electroabsorption modulated laser chip according to claim 1, characterized in that, The isolation region (2) includes an N-type InP substrate (21); a modulation region quantum well (22), a P-type InP cladding (25), a BCB insulating resin (26), an InGaAs contact layer (27), and a SiO2 insulating layer (28), specifically: A modulation region quantum well (22) is grown on an N-type InP substrate (21), and the modulation region quantum well (22) is etched with a predetermined width under a ridge waveguide structure; The SiO2 insulating layer (28) is filled in the etched modulation region quantum well (22) and the double trench structure, and the SiO2 insulating layer (28) is filled with BCB insulating resin (26). The P-type InP cladding (25) forms the spine structure on the modulation region quantum well (22) and the two outer walls on the channel structure.

4. The structure of the electroabsorption modulated laser chip according to claim 2, characterized in that, When the width of the laser quantum well (13) under the ridge waveguide structure of the laser region (1) is 18 μm, the width of the modulation region quantum well (32) under the ridge waveguide structure of the modulation region (3) is 25 μm.

5. The structure of the electroabsorption modulated laser chip according to claim 4, characterized in that, Also includes: In the ridge waveguide structure of the laser region (1), the width of the ridge structure is 2.2 μm, and the widths of the double grooves on both sides of the ridge structure are 16 μm respectively. The width of the spinal structure in the modulation area (3) is 4um, and the width of the double grooves on both sides of the spinal structure is 120um.

6. The structure of the electroabsorption modulated laser chip according to claim 5, characterized in that, The length of the laser region (1) is 320um, the length of the isolation region (2) is 50um, and the length of the modulation region (3) is 160um.

7. The structure of the electroabsorption modulated laser chip according to claim 5, characterized in that, In the region 15 μm away from the light-emitting surface of the modulation region (3), the corresponding BCB insulating resin is etched away, leaving the SiO2 insulating layer (18) covering the sidewall of the ridge structure and the surface of its dual-channel structure.

8. The structure of the electroabsorption modulated laser chip according to claim 7, characterized in that, In adjacent electroabsorption modulated laser chips on a wafer, the first electroabsorption modulated laser chip and the second electroabsorption modulated laser chip that are adjacent to each other are formed by connecting the laser region of the first electroabsorption modulated laser chip with the modulation region of the second electroabsorption modulated laser chip. The first and third electroabsorption modulated laser chips, which are adjacent to each other, are formed by P-type InP claddings that each contain a laser region, an isolation region, and a modulation region.

9. A method for manufacturing an electroabsorption modulated laser chip, characterized in that, This includes fabricating the structure of the electroabsorption modulated laser chip as described in any one of claims 1-7 through growth and etching processes.

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