CN218632788U - High-power and narrow-linewidth InP integrated semiconductor laser - Google Patents

Abstract

The utility model provides a high power, narrow linewidth InP integrated semiconductor laser relates to semiconductor laser's technical field for the big technical problem of the Bragg grating preparation technology degree of difficulty in solving DFB and DBR structure. The semiconductor laser comprises a lower electrode, a substrate, a lower limiting layer, an active layer and an upper limiting layer, wherein the lower electrode, the substrate, the lower limiting layer, the active layer and the upper limiting layer are sequentially arranged from bottom to top, a Bragg grating and a long-strip-shaped current injection layer are etched on the upper limiting layer, the Bragg grating is positioned on two sides of the current injection layer and is perpendicular to the current injection layer, and an isolation groove is formed between the current injection layer and the Bragg gratings on the two sides. The semiconductor laser adopts the lateral deep etching surface to replace the prior DFB and DBR structure, thereby avoiding secondary epitaxy and high-precision butt-joint alignment process. The semiconductor laser with the wide-strip high-power F-P cavity structure and poor spectral characteristics and light beam quality can also realize narrow linewidth and high light beam quality output.

Description

High-power and narrow-linewidth InP integrated semiconductor laser

Technical Field

The utility model relates to a semiconductor laser's technical field especially relates to an integrated semiconductor laser of high power, narrow linewidth InP.

Background

At present, narrow linewidth semiconductor lasers are mainly classified into two types: the inner cavity has a narrow line width and the outer cavity has a narrow line width. The intracavity InP-based narrow linewidth semiconductor laser is further divided into a distributed feedback bragg grating (DFB) structure and a Distributed Bragg Reflector (DBR) structure. The DFB and DBR inner cavity narrow linewidth semiconductor laser structure selects a longitudinal mode in a resonant cavity by introducing Bragg grating. The grating of the DFB semiconductor laser is distributed in the whole resonant cavity, the grating area of the DBR semiconductor laser is only arranged on two sides (or one side) and is only used as a reflector, and the grating is not arranged in the gain area and is separated from the reflector.

The DFB and DBR inner cavity narrow linewidth semiconductor laser has the problems of secondary epitaxial growth, high preparation cost, complex preparation process and the like. For example, patent publication No. CN111313229A discloses a distributed feedback semiconductor laser, which sequentially includes, from bottom to top, an N-plane electrode layer, a substrate layer, a buffer layer, a lower waveguide layer, an active layer, an upper waveguide layer, a secondary epitaxial grating layer, an etching self-stop layer, a cladding layer, an ohmic contact layer, a passivation layer, and a P-plane electrode layer; the cladding layer and the ohmic contact layer form a waveguide structure, and the waveguide structure is a ridge waveguide structure. Because the Bragg grating of the semiconductor laser with the DFB structure is positioned below or above the active region, secondary epitaxial growth is needed after the grating is prepared, so that external pollution is easily caused, the process preparation is complicated, and the yield is lower. The DBR structure semiconductor laser needs to perform high-precision alignment and butt joint of the ridge waveguide and the grating structure, which has extremely high requirements on the conditions of the photolithography process.

SUMMERY OF THE UTILITY MODEL

To the big technical problem of the Bragg grating preparation technology degree of difficulty in DFB and the DBR structure, the utility model provides a high power, narrow linewidth InP integrated semiconductor laser has avoided secondary epitaxy and high accuracy butt joint alignment technology for the semiconductor laser of wide strip high power F-P chamber structure that spectral characteristic and beam quality are poor also can realize narrow linewidth, high beam quality output.

In order to achieve the above purpose, the technical solution of the present invention is realized as follows:

the high-power and narrow-linewidth InP integrated semiconductor laser comprises a lower electrode, a substrate, a lower limiting layer, an active layer and an upper limiting layer which are sequentially arranged from bottom to top, wherein Bragg gratings and strip-shaped current injection layers are etched on the upper limiting layer, the Bragg gratings are positioned on two sides of the current injection layers and are vertical to the current injection layers, and isolation grooves are formed between the current injection layers and the Bragg gratings on the two sides.

The etching depth of the Bragg grating is smaller than the thickness of the upper limiting layer, so that the increase of the threshold current of the device is avoided, and the output power of the device is reduced.

The depth of the isolation groove is equal to the etching depth of the Bragg grating.

The Bragg grating structure is a rectangular grating, and the Bragg gratings are symmetrically distributed on two sides of the current injection layer.

The duty ratio of the Bragg grating is 0.5 to 0.8.

Preferably, the duty ratio of the Bragg grating is 0.5, so that the process preparation difficulty is reduced.

The Bragg grating is composed of a low-refractive-index material and a high-refractive-index material, the low-refractive-index material is located in a strip-shaped gap formed by the high-refractive-index material, and the high-refractive-index material is the same as the material of the upper limiting layer.

The low refractive index material is SiO ₂ 。

The lower electrode is made of Au-Ge-Ni.

The top of the current injection layer also comprises an ohmic contact layer and a P-surface electrode which are sequentially arranged from bottom to top, and the ohmic contact layer is made of a heavily doped material.

The P-side electrode is made of Ti-Pt-Au.

The utility model has the advantages that: the semiconductor laser adopts the lateral deep etching surface to replace the original DFB and DBR structure, and secondary epitaxy and high-precision butt-joint alignment process are avoided. The semiconductor laser with the wide-strip high-power F-P cavity structure and poor spectral characteristics and light beam quality can also realize narrow linewidth and high light beam quality output.

Drawings

In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the description below are only some embodiments of the present invention, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a schematic diagram of a semiconductor laser;

FIG. 2 is a top view of a semiconductor laser;

in the figure: 1. a lower electrode; 2. a substrate; 3. a lower confinement layer; 4. an upper confinement layer; 5. an active layer; 6. a Bragg grating; 7. a current injection layer; 8. and (6) isolating the groove.

Detailed Description

The technical solutions in the embodiments of the present invention will be described clearly and completely with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments in the present invention, all other embodiments obtained by a person skilled in the art without any creative effort belong to the protection scope of the present invention.

Example 1

An InP integrated semiconductor laser with high power and narrow linewidth comprises a lower electrode 1 (an N-surface electrode), a substrate 2, a lower limiting layer 3 (an N-surface limiting layer), an active layer 5 and an upper limiting layer 4 (a P-surface limiting layer), wherein the lower electrode 1, the substrate 2, the lower limiting layer 3 (an N-surface limiting layer), the active layer 5 and the upper limiting layer 4 (a P-surface limiting layer) are sequentially arranged from bottom to top, and the active layer 5 adopts a multi-quantum well structure. The upper limiting layer 4 is etched with a Bragg grating 6 and a strip-shaped current injection layer 7, and the width of the current injection layer 7 is prepared according to the specific requirements of the device. The Bragg gratings 6 are located on two sides of the current injection layer 7, the Bragg gratings 6 are perpendicular to the current injection layer 7, namely the Bragg gratings 6 are distributed along the direction of a resonant cavity of the semiconductor laser, and the direction of the resonant cavity of the semiconductor laser is along the direction of a natural cleavage plane of the semiconductor laser. An isolation groove 8 is formed between the current injection layer 7 and the Bragg gratings 6 on the two sides, the width of the isolation groove 8 is optimized according to the performance of a specific device, and the isolation groove 8 has two functions, namely, the Bragg gratings 6 are separated from the current injection layer 7, so that the change of the concentration of carriers caused by current injection is avoided, and the change of the refractive index of the Bragg gratings 6 is further avoided. The reason is that the corresponding Bragg wavelength changes after the refractive index of the Bragg grating 6 changes, and the characteristic of the output spectrum of the high-power and narrow-linewidth InP integrated semiconductor laser is that the wavelength changes, and even the unfavorable condition of multiple longitudinal modes occurs. And secondly, the heat dissipation of the semiconductor laser is improved, the isolation groove 8 has a function similar to a micro-channel structure, and the heat dissipation of the device is improved.

Example 2

A high-power and narrow-linewidth InP integrated semiconductor laser is disclosed, as shown in figure 1 and figure 2, the Bragg grating 6 is symmetrically distributed on two sides of a current injection layer 7, the etching depth of the Bragg grating 6 is smaller than the thickness of an upper limiting layer 4, and the grating etching depth exceeds an active layer 5 to cause high loss, so that the threshold current of the device is greatly increased, and the output power of the device is reduced. The depth of the isolation groove 8 is equal to the etching depth of the Bragg grating 6. The Bragg grating 6 is a rectangular grating, the duty ratio of the Bragg grating 6 is 0.3 to 0.8, and the duty ratio of the Bragg grating 6 is preferably 0.5 by combining the preparation difficulty of a process.

The bragg grating 6 is composed of a low refractive index material and a high refractive index material, the low refractive index material is located in a strip-shaped gap formed by the high refractive index material, and the period of the bragg grating 6 can be optimized by combining the process. The high refractive index material is the same as the upper limiting layer 4, and the low refractive index material is SiO ₂ . The Bragg grating 6 mainly acts on the principle that the periodic refractive index perturbation generated by the Bragg grating 6 is close to the current injection layer 7, the grating meets the Bragg condition, the wavelength of the semiconductor laser can be selected, and the line width narrowing of the device is further realized.

The other structure is the same as that of embodiment 1.

Example 3

A high-power and narrow-linewidth InP integrated semiconductor laser is disclosed, as shown in fig. 1 and fig. 2, the lower electrode 1 is made of Au-Ge-Ni, and the current injection layer 7 further comprises an ohmic contact layer and a P-surface electrode which are sequentially arranged from bottom to top. The P-side electrode is made of Ti-Pt-Au; the ohmic contact layer is made of heavily doped material (the doping concentration is higher than 1e18cm in general) ^-3 ）。

The other structure is the same as that of embodiment 2.

The preparation method of the high-power and narrow-linewidth InP integrated semiconductor laser comprises the following steps:

(1) A lower limiting layer 3, an active layer 5, an upper limiting layer 4 and other structures are grown on the substrate 2, wherein buffer layers, waveguide layers, etching stop layers and the like can also be included. The growth adopts MOCVD or MBE and the like.

(2) After the epitaxial structure is grown, the epitaxial structure is pretreated before process preparation. And then, glue homogenizing, exposing, developing and curing are carried out.

(3) And carrying out ICP etching by taking the photoresist as a mask, preparing a mesa current injection layer 7 and a Bragg grating 6 on the epitaxial wafer, and forming an isolation groove 8 between the current injection layer and the Bragg grating 6.

(4) Deposition of SiO on the upper confinement layer 4 ₂ An insulating film.

(5) Current injection using stripping liquidSiO of the cladding 7 ₂ The insulating film is subjected to a Lift-off process, and a P-side electrode is grown on the current injection layer 7.

(6) And (3) carrying out N-surface thinning and polishing on the high-power and narrow-linewidth InP integrated semiconductor laser to prepare an N-surface electrode.

(7) The Bar strips were cleaved by the laser and the cavity mask was prepared.

(8) And cleaving into single tubes and packaging to obtain the high-power and narrow-linewidth InP integrated semiconductor laser.

The above description is only a preferred embodiment of the present invention, and should not be taken as limiting the invention, and any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims (10)

1. The utility model provides a high power, narrow linewidth InP integrated semiconductor laser, its characterized in that includes lower electrode (1), substrate (2), lower limiting layer (3), active layer (5) and upper limiting layer (4) that set gradually from bottom to top, it has Bragg grating (6) and rectangular shape current injection layer (7) to etch on upper limiting layer (4), bragg grating (6) are located current injection layer (7) both sides, and Bragg grating (6) are perpendicular with current injection layer (7), are equipped with between current injection layer (7) and the Bragg grating (6) of both sides isolation tank (8).

2. A high power, narrow linewidth InP integrated semiconductor laser according to claim 1, wherein the bragg gratings (6) are symmetrically distributed on both sides of the current injection layer (7).

3. A high power, narrow linewidth InP integrated semiconductor laser as claimed in claim 2 wherein the bragg grating (6) structure is a rectangular grating.

4. A high power, narrow linewidth InP integrated semiconductor laser according to claim 3, wherein the bragg grating (6) in the upper confinement layer (4) is etched to a depth not exceeding the active layer (5).

5. A high power, narrow linewidth InP integrated semiconductor laser according to claim 4, wherein the depth of the isolation trenches (8) is equal to the depth of the etching of the bragg gratings (6).

6. A high power, narrow linewidth InP integrated semiconductor laser as claimed in claim 5 wherein the duty cycle of the Bragg grating (6) is 0.3 to 0.8.

7. A high power, narrow linewidth InP integrated semiconductor laser as claimed in claim 6 wherein the bragg grating (6) has a duty cycle of 0.5.

8. A high power, narrow linewidth InP integrated semiconductor laser according to any of claims 1-7, wherein the top of the current injection layer (7) further comprises an ohmic contact layer and a P-side electrode in that order from bottom to top.

9. The high power, narrow linewidth InP integrated semiconductor laser of claim 8, wherein the lower electrode is an Au-Ge-Ni electrode.

10. The high power, narrow linewidth InP integrated semiconductor laser of claim 9, wherein the P-plane electrode is a Ti-Pt-Au electrode.

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