HIGH-POWER EDGE-EMITTING SEMICONDUCTOR LASER WITH ASYMMETRIC STRUCTURE

Abstract

A high-power edge-emitting semiconductor laser with asymmetric structure, comprising: a substrate layer; a lower cladding layer; a lower optical waveguide layer; a first lower barrier layer; a quantum well layer; a first upper barrier layer; an upper optical waveguide layer, and make the thickness of the upper optical waveguide layer be below 300 nm, the thickness of the upper optical waveguide layer is ⅓˜½ of the thickness of the lower optical waveguide layer; an upper cladding layer, and make the thickness of the upper cladding layer be below 900 nm, the thickness of the upper cladding layer is ⅓˜½ of the thickness of the lower cladding layer; and an ohmic contact layer formed on the upper cladding layer.

Claims

1. A high-power edge-emitting semiconductor laser with asymmetric structure, comprising: a substrate layer 10, the material is n-type gallium arsenide (n-GaAs); a lower cladding layer 14, the material is n-type aluminum gallium indium phosphide (n-AlxGal-xInP, x is 0.2˜0.4)and formed on the substrate layer 10; a lower optical waveguide layer 16, the material is gallium indium phosphide (GalnP) and formed on the lower cladding layer 14; a first lower barrier layer 18, the material is gallium arsenide phosphide (GaAsP) and formed on the lower optical waveguide layer 16; a quantum well layer 22, the material is indium gallium arsenide (InGaAs) and formed on the first lower barrier layer 18; a first upper barrier layer 26, the material is gallium arsenide phosphide (GaAsP) and formed on the quantum well layer 22; an upper optical waveguide layer 28, the material is gallium indium phosphide (GalnP) and formed on the first upper barrier layer 26, and make the thickness of the upper optical waveguide layer 28 be below 300 nm, the thickness of the upper optical waveguide layer 28 is ⅓˜½ of the thickness of the lower optical waveguide layer 16; an upper cladding layer 30, the material is p-type aluminum gallium indium phosphide (p-AlxGal-xInP, x is 0.55˜0.9) and formed on the upper optical waveguide layer 28, and make the thickness of the upper cladding layer 30 be below 900 nm, the thickness of the upper cladding layer 30 is ⅓˜½ of the thickness of the lower cladding layer 14; and an ohmic contact layer 34, the material is p-type gallium arsenide (p-GaAs) and formed on the upper cladding layer 30.

2. The high-power edge-emitting semiconductor laser with asymmetric structure, as claimed in claim 1, wherein a second lower barrier layer 20 made of gallium arsenide (GaAs) is formed between the quantum well layer 22 and the first lower barrier layer 18, and a second upper barrier layer 24 made of gallium arsenide (GaAs) is formed between the quantum well layer 22 and the first upper barrier layer 26.

3. The high-power edge-emitting semiconductor laser with asymmetric structure, as claimed in claim 1, wherein a lower transition layer 12 made of n-type gallium indium phosphide (n-GalnP) is also formed between the substrate layer 10 and the lower cladding layer 14, and an upper transition layer 32 made of layer p-type gallium indium phosphide (p-GaInP) is also formed between the upper cladding layer 30 and the ohmic contact layer 34.

4. The high-power edge-emitting semiconductor laser with asymmetric structure, as claimed in claim 3, wherein the material of the lower transition layer 12 is n-Ga0.51In0.49P, the thickness of the lower cladding layer 14 is 2200 nm and the material is n-(Al0.2Ga0.8)In0.5P, the thickness of the lower optical waveguide layer 16 is 800 nm and the material is Ga0.5In0.49P, the material of the first lower barrier layer 18 is Ga0.8AsP0.2, the second lower barrier layer 20 thickness is 2˜5 nm, the material of the quantum well layer 22 is In0.2Ga0.8As and the thickness of the quantum well layer 22 is 5˜10 nm, the thickness of the second upper barrier layer 24 is 2˜5 nm, the material of the first upper barrier layer 26 is Ga0.8AsP0.2, the thickness of the upper optical waveguide layer 28 is 300 nm and the material is Ga0.51In0.49P, the thickness of the upper cladding layer 30 is 845 nm and the material is p-(Al0.65Ga0.35)In0.5P, and the material of the upper transition layer 32 is p-Ga0.51In0.49P

5. The high-power edge-emitting semiconductor laser with asymmetric structure, as claimed in claim 1, wherein the crystal orientation angle of the substrate layer 10 deviates for (100) 10 degrees.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0014] FIG. 1 is a schematic diagram of the structure of the present invention;

[0015] FIG. 2 is a schematic diagram illustrating f of the correlation between various asymmetric structures of the present invention and the light intensity rate in area other than P-type doping.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

[0016] Referring to FIG. 1, the present invention from bottom to top are: n-GaAs substrate layer 10, n-Ga.sub.0.51In.sub.0.49P lower transition layer 12, n-(Al.sub.0.2Ga.sub.0.8)In.sub.0.5P lower cladding layer 14 with a thickness of 2200 nm, Ga.sub.0.51In.sub.0.49P lower optical waveguide layer 16 with a thickness of 800 nm, Ga.sub.0.8AsP.sub.0.2 first lower barrier layer 18, GaAs second lower barrier layer 20 with thickness of 2˜5 nm, In.sub.0.2Ga.sub.0.8 quantum well layer 22 with thickness of 5-10 nm, GaAs second upper barrier layer 24 with thickness of 2-5 nm, Ga.sub.0.8AsP.sub.0.2 first upper barrier layer 26, Ga.sub.0.51In.sub.0.49P upper optical waveguide layer 28 with thickness of 300 nm, p-(Al.sub.0.65Ga.sub.0.35)In.sub.0.5P upper cladding layer with a thickness of 845 nm, p-Ga.sub.0.51In.sub.0.49P upper transition layer 32 and a p-GaAs ohmic contact layer 34.

[0017] With the features disclosed above, the present invention is a 976 nm high-power semiconductor laser with an asymmetric structure without aluminum active area, the material epitaxial part is grown on the GaAs substrate layer 10 with a deviation (100) from the crystal orientation angle of degrees, and the active area stress compensation structure is inserted with 2˜5 nm barrier layers 20,24, the PL wavelength of the quantum well layer 22 is designed at 965 nm, and under high current, the electroluminescence (EL) wavelength corresponding to this photoluminescence (PL) wavelength can reach 976 nm; Therefore, by adjusting the different thicknesses of the upper and lower optical waveguide layers 28, 16 and the different compositions and thicknesses of the upper and lower cladding layers 30, 14, make more than 90% of the optical field falls outside the area of the p-doping, the internal loss is minimized, and the thermal resistance of the device in high-power operation is reduced by shortening the thickness of the P-type doped side;

[0018] FIG. 2 is showing the thickness of the upper optical waveguide layer 28 with a thickness of 150 nm or 300 nm and the upper cladding layer 30 with different aluminum compositions corresponds to the lower optical waveguide layer 16 with a thickness of 800 nm, and the proportion of the optical field outside the area of p-doping is≥93%.

[0019] The present invention introduces an asymmetric decoupled confinement heterostructure (ADCH) structure to reduce internal loss and increase SE; the thickness of the upper optical waveguide layer 28 is smaller than the thickness of the lower optical waveguide layer 16, and the thickness of the upper cladding layer 30 is smaller than the thickness of the lower cladding layer 14, so the position of the active area is shifted to be close to the upper cladding layer 30, the refractive index of the lower cladding layer 14 is higher than that of the upper cladding layer 30, which can greatly reduce the optical field absorbing by the free carriers falling on the upper cladding layer 30, and the optical confinement factor Γ.sub.p-WG<Γ.sub.n-WG and Γ.sub.QW becomes smaller and the equivalent light spot becomes larger, according to the following formula P.sub.max=(d.sub.qw/Γ.sub.qw)*W*[1−R/(1+R)]*P.sub.COMD(P.sub.max: maximum output power, d.sub.qw: quantum well width, Γ.sub.qw: confinement factor, R: front mirror surface specular reflectance, P.sub.COMD: maximum output power that can withstand from COMD) can be structurally improving the output optical power, and has the effect of using the asymmetric structure to improve the output optical power; at the same time, the active area is Al-free material, which also helps to improve the COMD level, which has the effect of increasing the reliability of the components.

[0020] Although particular embodiments of the invention have been described in detail for purposes of illustration, various modifications and enhancements may be made without departing from the spirit and scope of the invention.

[0021] Accordingly, the invention is not to be limited except as by the appended claims.