Dual facet light emitting laser and method of making the same

Abstract

The application provides a double-end-face light-emitting laser and a preparation method thereof. The double-end-face light-emitting laser comprises a substrate, a rear grating area formed on the substrate, and phase areas, gain areas, front grating areas and modulator areas symmetrically distributed on both sides of the rear grating area from near to far. The rear grating area and the front grating area are composed of grating layers, and the grating layers of the rear grating area and the front grating area have gratings on surfaces. The application doubles the rate and wavelength tuning performance of the laser, and provides a new optical transmitting chip solution for an optical communication system.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of semiconductor optoelectronic integrated devices, and relates to a laser, in particular to a double-end-face light-emitting laser and a preparation method thereof. BACKGROUND

[0002] With the rapid development of 5G network, the performance of optical fiber communication system for optical transmitting chip is put forward higher requirements, in which high speed and multi-wavelength coverage are two important development directions to meet the needs of the Internet. The speed of optical transmitting chip is restricted by physical mechanism and process precision, so it is more and more difficult to improve the speed. In order to solve the problem of speed improvement, bandwidth expansion technology and external modulation technology are often used. Multi-wavelength coverage is to make full use of the existing network fiber resources to meet the different application scenarios of the Internet. At present, the multi-wavelength scheme usually adopts parallel multiple fixed wavelength lasers or wavelength tunable lasers. These technologies will bring many problems: the integration of the chip is large, the size is large, the power consumption is high and the cost is increased. SUMMARY

[0003] (I) Technical problems to be solved

[0004] Therefore, the present application provides a double-end-face light-emitting laser and a preparation method thereof, which at least partly solve the above problems.

[0005] (II) Technical solutions

[0006] The present application provides a double-end-face light-emitting laser, which comprises: a substrate; a rear grating area formed on the substrate, and phase areas, gain areas, front grating areas and modulator areas are symmetrically distributed on both sides of the rear grating area from near to far; wherein the rear grating area and the front grating area are composed of a grating layer, and the grating layer surface of the rear grating area and the front grating area has a grating.

[0007] Optionally, the band gap wavelength of the modulator area is 10-100nm shorter than that of the gain area.

[0008] Optionally, the band gap wavelength of the rear grating area, the front grating area and the phase area is 90-200nm shorter than that of the gain area.

[0009] Optionally, the double-end-face light-emitting laser further comprises: the gain area is composed of a first lower waveguide layer, a first multi-quantum well active area and a first upper waveguide layer which are stacked on the substrate in sequence; the modulator area is composed of a second lower waveguide layer, a second multi-quantum well active area and a second upper waveguide layer which are stacked on the substrate in sequence; an inverted mesa shallow ridge waveguide is formed on the first upper waveguide layer, the second upper waveguide layer and the grating layer, and the inverted mesa shallow ridge waveguide comprises a cladding layer and an electrical contact layer from bottom to top; a P electrode is formed on the surface of the inverted mesa shallow ridge waveguide; and an N electrode is formed at the bottom of the substrate.

[0010] Optionally, the grating layer has a thickness of a total thickness of the first lower waveguide layer, the first multi-quantum well active region and the first upper waveguide layer.

[0011] In another aspect, the application provides a method for manufacturing the above-mentioned double-end-face light-emitting laser, comprising: sequentially forming the first lower waveguide layer, the first multi-quantum well active region and the first upper waveguide layer on the substrate; manufacturing the first SiO2 strip structure on the first upper waveguide layer; etching away the first lower waveguide layer, the first multi-quantum well active region and the first upper waveguide layer except for the first SiO2 strip structure, and growing the second lower waveguide layer, the second multi-quantum well active region and the second upper waveguide layer in butt joint; removing the first SiO2 strip structure and manufacturing the second SiO2 strip structure on the first upper waveguide layer and the second upper waveguide layer; etching away the first lower waveguide layer, the first multi-quantum well active region, the first upper waveguide layer, the second lower waveguide layer, the second multi-quantum well active region and the second upper waveguide layer except for the second SiO2 strip structure, and growing the grating layer in butt joint; manufacturing the grating on the surface of the grating layer; forming the cladding layer and the electrical contact layer on the first upper waveguide layer, the second upper waveguide layer and the surface of the grating layer, and manufacturing the cladding layer and the electrical contact layer into the inverted mesa shallow ridge waveguide; performing photoetching on the electrical contact layer and performing ion implantation; manufacturing the P electrode on the inverted mesa shallow ridge waveguide and manufacturing the N electrode at the bottom of the substrate.

[0012] Optionally, manufacturing the first SiO2 strip structure on the first upper waveguide layer comprises: growing the SiO2 layer on the first upper waveguide layer;

[0013] The first SiO2 strip structure is manufactured on the gain region and the gain region by photoetching and wet etching.

[0014] Optionally, removing the first SiO2 strip structure and manufacturing the second SiO2 strip structure on the first upper waveguide layer and the second upper waveguide layer comprises: etching away the first SiO2 strip structure; growing the SiO2 layer on the second upper waveguide layer and the first upper waveguide layer; and manufacturing the second SiO2 strip structure on the modulator region and the modulator region and the gain region and the gain region by photoetching and wet etching.

[0015] Optionally, etching away the first lower waveguide layer, the first multi-quantum well active region and the first upper waveguide layer except for the first SiO2 strip structure and etching away the first lower waveguide layer, the first multi-quantum well active region, the first upper waveguide layer, the second lower waveguide layer, the second multi-quantum well active region and the second upper waveguide layer except for the second SiO2 strip structure comprises: performing RIE etching by using CH4 and H2; and cleaning the substrate by using trichloroethylene, acetone and ethanol respectively after etching; and etching the defects by using H2SiO4 and H2O2.

[0016] Optionally, performing photoetching on the electrical contact layer and performing ion implantation comprises: photoetching the isolation groove pattern on the electrical contact layer; etching the electrical isolation groove and performing He ion implantation.

[0017] (III) Beneficial Effects

[0018] The application integrates two wavelength tunable electric absorption lasers together by back-to-back, shares a distributed Bragg grating region, emits laser light from two end faces, realizes the effect of doubling the rate and wavelength tuning performance, reduces the power consumption of the Bragg grating region, and provides a new optical transmitter chip solution for an optical communication system. BRIEF DESCRIPTION OF DRAWINGS

[0019] Figure 1 A flowchart of a preparation method of a double-end-face light-emitting laser provided by the application is schematically shown;

[0020] Figure 2 A schematic diagram of step S1 of the preparation method of the double-end-face light-emitting laser provided by the application is schematically shown;

[0021] Figure 3 A top view of step S2 of the preparation method of the double-end-face light-emitting laser provided by the application is schematically shown;

[0022] Figure 4 and Figure 5 A schematic diagram of step S3 of the preparation method of the double-end-face light-emitting laser provided by the application is schematically shown;

[0023] Figure 6 A schematic diagram of step S4 of the preparation method of the double-end-face light-emitting laser provided by the application is schematically shown;

[0024] Figure 7 and Figure 8 A schematic diagram of step S5 of the preparation method of the double-end-face light-emitting laser provided by the application is schematically shown;

[0025] Figure 9 A schematic diagram of step S6 of the preparation method of the double-end-face light-emitting laser provided by the application is schematically shown;

[0026] Figure 10 A schematic diagram of step S7 of the preparation method of the double-end-face light-emitting laser provided by the application is schematically shown;

[0027] Figure 11 A schematic diagram of step S8 of the preparation method of the double-end-face light-emitting laser provided by the application is schematically shown;

[0028] Figure 12 A schematic diagram of step S9 of the preparation method of the double-end-face light-emitting laser provided by the application is schematically shown. DETAILED DESCRIPTION

[0029] In order to make the objects, technical solutions and advantages of the present application clearer, the present application will be further described in detail below with reference to specific embodiments and with reference to the drawings.

[0030] Referring to Figure 12 , Figure 12 The structure of the double-end-face light-emitting laser provided by the present application is schematically shown, and the present application provides a double-end-face light-emitting laser, which comprises a substrate, a rear grating area formed on the substrate, and phase areas, gain areas, front grating areas and modulator areas symmetrically distributed in sequence from near to far on both sides of the rear grating area; wherein the rear grating area and the front grating area are composed of a grating layer, and the grating layer surface of the rear grating area and the front grating area has a grating; the phase areas are composed of the same material as the grating layer; the gain areas are composed of a first lower waveguide layer, a first multi-quantum well active area and a first upper waveguide layer stacked in sequence on the substrate; and the modulator areas are composed of a second lower waveguide layer, a second multi-quantum well active area and a second upper waveguide layer stacked in sequence on the substrate. Figure 12 As shown in the figure, the areas 1 and 5 are modulator areas, the areas 2 and 6 are rear grating areas, the areas 3 and 7 are laser gain areas, the areas 4 and 8 are phase areas, and the area 9 is a rear grating area, and the areas are distinguished by dashed lines. The thicknesses of the first lower waveguide layer, the first multi-quantum well active area and the first upper waveguide layer and the second lower waveguide layer, the second multi-quantum well active area and the second upper waveguide layer are independently optimized according to performance; and the thickness of the grating layer is the total thickness of the first lower waveguide layer, the first multi-quantum well active area and the first upper waveguide layer.

[0031] The double-end-face light-emitting laser provided by the present application integrates two wavelength-tunable electric absorption lasers together, shares a distributed Bragg grating area, emits laser light from two end faces, and realizes the effect of doubling the rate and wavelength tuning performance.

[0032] In an embodiment of the present application, the band gap wavelength of the modulator area is 10-100 nm shorter than that of the gain area. The band gap wavelengths of the rear grating area, the front grating area and the phase area are 90-200 nm shorter than that of the gain area. The band gap wavelength of the modulator is short, and a reverse bias is applied during operation to cause red shift of the absorption spectrum and absorption of the generated laser light of the absorption laser; and the band gap wavelengths of the grating area and the phase area are short, and the generated laser light of the laser passes through these areas without being absorbed.

[0033] In another embodiment of the present application, the double-end-face light-emitting laser further comprises an inverted mesa shallow ridge waveguide formed on the first upper waveguide layer, the second upper waveguide layer and the grating layer, wherein the inverted mesa shallow ridge waveguide comprises a cladding layer and an electrical contact layer from bottom to top; a P electrode formed on the surface of the inverted mesa shallow ridge waveguide; and an N electrode formed on the bottom of the substrate.

[0034] Referring to Figure 1 , Figure 1The flow chart of the preparation method of the double-end-face light-emitting laser as described above is shown schematically, comprising:

[0035] S1, sequentially forming a first lower waveguide layer 11, a first multi-quantum well active region 12 and a first upper waveguide layer 13 on a substrate 10;

[0036] S2, preparing a first SiO2 strip structure 14 on the first upper waveguide layer 13;

[0037] S3, etching away the first lower waveguide layer 11, the first multi-quantum well active region 12 and the first upper waveguide layer 13 except for the first SiO2 strip structure 14 and growing a second lower waveguide layer 15, a second multi-quantum well active region 16 and a second upper waveguide layer 17 by butt joint growth;

[0038] S4, removing the first SiO2 strip structure 14 and preparing a second SiO2 strip structure 18 on the first upper waveguide layer 13 and the second upper waveguide layer 17;

[0039] S5, etching away the first lower waveguide layer 11, the first multi-quantum well active region 12, the first upper waveguide layer 13, the second lower waveguide layer 15, the second multi-quantum well active region 16 and the second upper waveguide layer 17 except for the second SiO2 strip structure 18 and growing a grating layer 19 by butt joint growth;

[0040] S6, preparing a grating 20 on the surface of the grating layer 19;

[0041] S7, forming a cladding layer 21 and an electrical contact layer 22 on the surface of the first upper waveguide layer 13, the second upper waveguide layer 17 and the grating layer 19 and preparing a layer of the cladding layer 21 and the electrical contact layer 22 into a shallow ridge waveguide;

[0042] S8, performing photolithography on the electrical contact layer 22 and performing ion implantation;

[0043] S9, preparing a P electrode 24 on the shallow ridge waveguide and an N electrode 25 at the bottom of the substrate 10.

[0044] In the step S2, a SiO2 layer is grown on the first upper waveguide layer 13 and the first SiO2 strip structure 14 is prepared on the gain region 3 and the gain region 7 by using photolithography and wet etching.

[0045] The step S4 comprises: etching away the first SiO2 strip structure 14; growing a SiO2 layer on the second upper waveguide layer 17 and the first upper waveguide layer 13; and preparing the second SiO2 strip structure 18 on the modulator region 1 and the modulator region 5 and the gain region 3 and the gain region 7 by using photolithography and wet etching.

[0046] Step S3 and step S5 include: using CH4 and H2 to perform RIE etching; after etching, using trichloroethylene, acetone and ethanol to clean the substrate 10 respectively; using H2SiO4 and H2O2 to etch the defects.

[0047] Step S8 includes: photoetching an isolation groove pattern on the electrical contact layer 22; etching the electrical isolation groove and performing He ion implantation.

[0048] The following will be described in combination with specific embodiments.

[0049] S1, selecting an N-type indium phosphide substrate 10, using metal organic chemical vapor deposition (MOCVD) to grow InGaAsP lower waveguide layer 11 (band gap wavelength is 1200 nm), multi-quantum well active region 12 (band gap wavelength is 1550 nm), upper waveguide layer 13 (band gap wavelength is 1200 nm) on the substrate in sequence. The growth temperature is 680°C, the growth pressure is 100 mbar, the thickness of the upper and lower waveguide layers is 90 nm, there are 5 compressive strain well layers, each layer is 5 nm thick, there are 6 tensile strain barrier layers, each layer is 9 nm thick, and the multi-quantum well active region 12 is sandwiched between the lower waveguide layer 11 and the upper waveguide layer 13 to form a sandwich structure. As shown in Figure 2 .

[0050] S2, growing a 150 nm thick SiO2 layer on the upper waveguide layer 13, the growth temperature is 300°C, the growth pressure is 100 Pa; using a 1 μm thick photoresist mask, using a buffer oxide etching solution (BOE) to etch a 30 μm wide first SiO2 strip structure 14 to protect the laser gain region, the plan view is as shown in Figure 3 .

[0051] S3, using RIE method to etch away the InGaAsP material outside the laser gain region (3 and 7 regions) mask, the reaction etching pressure is 0.067 mbar, the power is 150 W, the reaction gas is CH4:H2=18:45, the etching time is 5 minutes, as shown in Figure 4 . Respectively using trichloroethylene, acetone and ethanol to clean the substrate 10, using H2SiO4 and H2O2 to etch away the remaining InGaAsP material after RIE etching, soaking the substrate in a concentrated H2SiO4 solution for 20 seconds for surface passivation; then rinsing with deionized water and spinning dry; using MOCVD to grow InGaAsP lower waveguide layer 15 (band gap wavelength is 1200 nm), multi-quantum well active region 16 (band gap wavelength is 1500 nm), upper waveguide layer 17 (band gap wavelength is 1200 nm) in sequence. The growth temperature is 680°C, the growth pressure is 100 mbar, the thickness of the upper and lower waveguide layers is 90 nm, there are 5 compressive strain well layers, each layer is 9 nm thick, there are 6 tensile strain barrier layers, each layer is 5 nm thick, as shown in Figure 5As shown.

[0052] S4. The first SiO2 strip structure 14 is removed by etching, and a new SiO2 layer is grown. A second SiO2 strip structure 18, 20 μm wide, is then formed in the laser gain region and modulator region using photolithography and wet etching. Figure 6 As shown.

[0053] S5. The InGaAsP material, excluding the second SiO2 strip structure 18, was etched using the RIE method. The reaction etching pressure was 0.067 mbar, the power was 150 W, the reaction gas was CH4∶H2=18∶45, and the etching time was 5 minutes. Figure 7 As shown. Substrate 10 was cleaned with trichloroethylene, acetone, and ethanol, respectively. The remaining InGaAsP material from the RIE etching was etched away with H2SiO4 and H2O2. After drying the substrate 10, it was immersed in a concentrated H2SiO4 solution for 20 seconds for surface passivation. Then it was rinsed with deionized water and dried. The grating layers 19 in the grating regions (regions 2, 6, and 9) and phase regions (regions 4 and 8) before and after growth were joined using MOCVD. InGaAsP material was used, the growth temperature was 630℃, and the growth pressure was 100 mbar. Its bandgap wavelength (1400 nm) is smaller than the laser emission wavelength, such as... Figure 8 As shown.

[0054] S6. Fabricate gratings 20 on the surface of grating layer 19 in the front and rear grating regions (regions 2, 6, and 9), as follows: Figure 9 As shown.

[0055] S7. A P-type Zn-doped InP cladding layer 21 (1500 nm thick) and an InGaAs electrical contact layer 22 (200 nm thick) are grown by MOCVD on the surfaces of the first upper waveguide layer 13, the second upper waveguide layer 17, and the grating layer 19 at a growth temperature of 630℃ and a growth pressure of 100 mbar. A 3 μm strip mask is photolithographically etched onto the cladding layer 21 and the electrical contact layer 22 using 1 μm photoresist. An inverted shallow ridge waveguide structure is then fabricated using etchants Br2∶HBr∶H2O = 1∶25∶80 (etching time 40 seconds) and HCl∶H2O = 9∶1 (etching time 3 minutes). The cross-sectional view is shown below. Figure 10 As shown.

[0056] S8. Photolithographically pattern the isolation trench on the electrical contact layer 22 using a 3μm thick photoresist. Etch with an etchant solution of H2SiO4∶H2O2∶H2O = 3∶1∶1 for 10 seconds to create electrical isolation trenches (50μm wide) between each region. Simultaneously, He ion implantation 23 is performed on the isolation trenches at an implantation energy of 200keV and an implantation dose of 10. 14 cm -2 Electrical isolation is achieved between different functional areas, such as Figure 11 As shown.

[0057] S9, P-face electrodes 24 are made on the electrode contact layer 22, and N-face electrodes 25 are made on the bottom after the substrate 10 is thinned, as shown. Figure 11

[0058] The above detailed embodiments further explain the purpose, technical solutions and advantages of the present application. It should be understood that the above are only specific embodiments of the present application and are not intended to limit the present application. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.​

Claims

1. A dual-end-face laser, characterized in that, include: Substrate (10); A rear grating region (9) is formed on the substrate. On both sides of the rear grating region (9), phase region (4, 8), gain region (3, 7), front grating region (2, 6), and modulator region (1, 5) are symmetrically distributed from near to far. The rear grating region (9) and the front grating region (2, 6) are composed of a grating layer (19), and the surface of the grating layer (19) has a grating (20). The gain regions (3, 7) are composed of a first lower waveguide layer (11), a first multi-quantum well active region (12) and a first upper waveguide layer (13) stacked sequentially on the substrate (10). The modulator region (1, 5) is composed of a second lower waveguide layer (15), a second multi-quantum well active region (16) and a second upper waveguide layer (17) stacked sequentially on the substrate (10); A shallow ridge waveguide is formed on the first upper waveguide layer (13), the second upper waveguide layer (17) and the grating layer (19). The shallow ridge waveguide includes a cladding layer (21) and an electrical contact layer (22) from bottom to top. An isolation region pattern is etched on the electrical contact layer (22) to achieve electrical isolation. P-electrode (24) is formed on the surface of the inverted shallow ridge waveguide; The N electrode (25) is formed on the bottom of the substrate (10).

2. The dual-end-face laser according to claim 1, characterized in that, The bandgap wavelength of the modulator region (1, 5) is 10-100 nm shorter than that of the gain region (3, 7).

3. The dual-end-face laser according to claim 1, characterized in that, The bandgap wavelengths of the rear grating region (9), the front grating region (2, 6), and the phase region (4, 8) are 90-200 nm shorter than those of the gain region (3, 7).

4. The dual-end-face laser according to claim 1, characterized in that, The thickness of the grating layer (19) is the total thickness of the first lower waveguide layer (11), the first multi-quantum well active region (12), and the first upper waveguide layer (13).

5. A method for fabricating a dual-end-face laser according to any one of claims 1 to 4, characterized in that, include: A first lower waveguide layer (11), a first multi-quantum well active region (12), and a first upper waveguide layer (13) are sequentially formed on the substrate (10). A SiO2 layer is grown on the first upper waveguide layer (13); The first SiO2 strip structure (14) was prepared in the gain region (3, 7) by photolithography and wet etching. The first lower waveguide layer (11), the first multi-quantum well active region (12) and the first upper waveguide layer (13) covered by the first SiO2 strip structure (14) are etched away, and the second lower waveguide layer (15), the second multi-quantum well active region (16) and the second upper waveguide layer (17) are grown in a docking manner. The first SiO2 strip structure (14) is removed by corrosion. SiO2 layers are grown on the second upper waveguide layer (17) and the first upper waveguide layer (13); The second SiO2 strip structure (18) was prepared in the modulator region (1, 5) and the gain region (3, 7) by photolithography and wet etching. The first lower waveguide layer (11), the first multi-quantum well active region (12), the first upper waveguide layer (13), the second lower waveguide layer (15), the second multi-quantum well active region (16) and the second upper waveguide layer (17) covered by the second SiO2 strip structure (18) are etched away and a grating layer (19) is grown. A grating (20) is fabricated on the surface of the grating layer (19); A cladding layer (21) and an electrical contact layer (22) are formed on the surfaces of the first upper waveguide layer (13), the second upper waveguide layer (17), and the grating layer (19), and the cladding layer (21) and the electrical contact layer (22) are fabricated into a layered inverted shallow ridge waveguide; The electrical contact layer (22) is photolithographically etched and then ion implanted. A P-electrode (24) is fabricated on the inverted shallow ridge waveguide and an N-electrode (25) is fabricated on the bottom of the substrate (10).

6. The preparation method according to claim 5, characterized in that, The etching away of the first lower waveguide layer (11), the first multi-quantum well active region (12), and the first upper waveguide layer (13) covered by the first SiO2 strip structure (14), and the etching away of the first lower waveguide layer (11), the first multi-quantum well active region (12), the first upper waveguide layer (13), the second lower waveguide layer (15), the second multi-quantum well active region (16), and the second upper waveguide layer (17) covered by the second SiO2 strip structure (18) includes: RIE etching was performed using CH4 and H2; After etching, the substrate (10) is cleaned with trichloroethylene, acetone and ethanol respectively; The defects in the etching were removed by using H2SiO4 and H2O2.

7. The preparation method according to claim 5, characterized in that, The process of photolithography and ion implantation of the electrical contact layer (22) includes: An isolation trench pattern is photolithographically formed on the electrical contact layer (22); The electrostatic isolation trench was corroded and He ion implantation was performed.

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