Large cross section ridge waveguide base transverse mode high power semiconductor laser

Abstract

The application relates to a large-section ridge waveguide base transverse mode high-power semiconductor laser, which comprises a substrate and a buffer layer, an N limiting layer, an N waveguide layer, a quantum well active layer, a P waveguide layer, a P limiting layer and a P contact layer arranged on the substrate in sequence; the P contact layer is formed with a first groove and a second groove penetrating the P contact layer and the P limiting layer and extending into the P waveguide layer through etching; the first groove and the second groove are arranged in parallel, and a ridge waveguide is formed in the unetched part between the first groove and the second groove. In the application, the thickness of the N waveguide layer is greater than that of the P waveguide layer, so that the optical field is pulled to the N doped area, thereby reducing the optical loss; the effective refractive index difference of the ridge structure and the effective refractive index difference on both sides is still less than 0.5% under the condition of increasing the ridge waveguide width; the spot size is increased, the influence of COMD is effectively reduced, and the output optical power is improved while realizing the base transverse mode output and keeping good beam quality.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of high-power semiconductor laser, and relates to a large-section ridge waveguide base transverse mode high-power semiconductor laser. BACKGROUND

[0002] High-power semiconductor lasers are widely used, and maintaining base transverse mode output and improving laser output beam quality are currently research hotspots of high-power semiconductor lasers, however, for base transverse mode semiconductor lasers, good beam quality and high output power are difficult to achieve simultaneously, and in the past few decades, developing high-power, reliable and efficient base transverse mode semiconductor lasers has been a challenge.

[0003] Semiconductor lasers usually use a ridge waveguide structure to achieve base transverse mode output, and the narrower the ridge width, the closer the transmission mode of the waveguide to single mode. In base transverse mode semiconductor lasers, the power is often limited by catastrophic optical mirror damage (COMD) of the resonant cavity surface, which is caused by temperature exceeding the melting point of the laser crystal material, and the design consideration of high-power semiconductor lasers is to increase the size of the resonant cavity surface to increase the COMD threshold, however, as the waveguide layer thickness and the ridge width increase, the laser will begin to support multiple mode resonances, making it difficult to maintain base transverse mode characteristics, and some structures increase the size of the cavity surface while using a tapered waveguide structure and an inclined grating distributed feedback structure to ensure base transverse mode output, however, this will result in unstable beam quality and increase the difficulty of manufacturing process. To achieve base transverse mode operation, the size of the laser ridge waveguide is difficult to increase, and the lateral ridge width range can only be limited to 3-5 mu m, which is difficult to achieve high-power output. SUMMARY

[0004] In view of the above problems of the prior art, the technical problem to be solved by the present application is to provide a large-section ridge waveguide base transverse mode high-power semiconductor laser.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0006] A large-section ridge waveguide base transverse mode high-power semiconductor laser comprises

[0007] A substrate is made of N-doped material;

[0008] A buffer layer is covered on the substrate, and the buffer layer is made of N-doped material;

[0009] An N confinement layer is covered on the buffer layer, and the N confinement layer is made of N-doped material;

[0010] An N waveguide layer is covered on the N confinement layer, and the N waveguide layer is made of unintentional doping or N-doped material;

[0011] a quantum well active layer overlying the N waveguide layer, the quantum well active layer being of undoped material;

[0012] a P waveguide layer overlying the quantum well active layer, the P waveguide layer being of unintentionally doped or P-type doped material, the P waveguide layer having a thickness less than the thickness of the N waveguide layer;

[0013] a P confinement layer overlying the P waveguide layer, the P confinement layer being of P-type doped material; and

[0014] a P contact layer overlying the P confinement layer, the P contact layer being of P-type doped material;

[0015] the P contact layer is formed with a first trench and a second trench through the P contact layer and the P confinement layer and into the P waveguide layer by etching, the etching depth being 0.6 μm to 2 μm, the first trench and the second trench being arranged in parallel, a ridge waveguide being formed in the unetched portion between the first trench and the second trench.

[0016] Further, the trench width of the first trench and the second trench is 10 μm to 50 μm; the lateral ridge width of the ridge waveguide is 8 μm to 10 μm, and the cavity length of the ridge waveguide is 1 mm to 5 mm.

[0017] Further, the substrate is an N-type doped GaAs substrate, the doping atom is silicon atom, and the doping concentration is 2.0 x 10 17 cm -3 to 2.0 x 10 18 cm -3 .

[0018] Further, the buffer layer is N-type doped GaAs material, the doping atom is silicon atom, and the doping concentration is 1 x 10 18 cm -3 to 5 x 10 18 cm -3 ; the thickness of the buffer layer is 0.2 μm to 2 μm.

[0019] Further, the N confinement layer is N-type doped AlGaAs material or AlGaInP material, the doping atom is silicon atom, and the doping concentration is 0.5 x 10 18 cm -3 to 2 x 10 18 cm -3 ; the thickness of the N confinement layer is 0.2 μm to 1.5 μm.

[0020] Further, the N waveguide layer is N-type doped AlGaAs material or GaInP material, the doping atom is silicon atom, and the doping concentration is 0 cm -3 to 5 x 1017 cm -3 ; the thickness of the N waveguide layer is 0.5-4 μm.

[0021] Further, the quantum well active layer is made of undoped InGaAsP material or undoped InAlGaAs material, and the thickness of the quantum well active layer is 4-15 nm.

[0022] Further, the P waveguide layer is made of P-type doped AlGaAs material or GaInP material, the doping atom is Zn atom, C atom or Mg atom, and the doping concentration is 0-5×10 -3 cm 17 -3 ; the thickness of the P waveguide layer is 0.5-2 μm.

[0023] Further, the P confinement layer is made of P-type doped AlGaAs material or AlGaInP material, the doping atom is Zn atom, C atom or Mg atom, and the doping concentration is 0.5×10 18 cm -3 -2×10 18 cm -3 ; the thickness of the P confinement layer is 0.2-1.5 μm.

[0024] Further, the P contact layer is made of P-type doped GaAs material, the doping atom is Zn atom or C atom, and the doping concentration is 2×10 19 cm -3 -1×10 20 cm -3 ; the thickness of the P contact layer is 0.1-0.3 μm.

[0025] In the present application, in view of the limitations of the prior art semiconductor laser, an epitaxial structure is provided, a ridge waveguide is formed by etching the contact layer to control the base transverse mode operation of the laser and guide the light transmission in the laser; by making the thickness of the N waveguide layer greater than that of the P waveguide layer, the light field is pulled to the N doped region, thereby reducing the light loss. By designing the groove size and selecting the material, doping atom and concentration of each layer, the effective refractive index difference between the ridge structure and the two sides can still be less than 0.5% even if the ridge width is increased, stable base transverse mode lasing can still be maintained when the ridge width is 8-10 μm, the spot size is greatly increased, the cavity surface power density is effectively reduced, high power output is achieved without causing COMD, the stability and long-term reliability of high power operation are improved, thereby maintaining the base transverse mode lasing while increasing the ridge width. BRIEF DESCRIPTION OF DRAWINGS

[0026] ​The accompanying drawings, which are included to provide a further understanding of this application and form part of this application, illustrate exemplary embodiments and are used to explain this application, but do not constitute an undue limitation of this application. In the drawings:

[0027] Figure 1 This is a schematic diagram of a preferred embodiment of the large-section ridge waveguide-based transverse-mode high-power semiconductor laser of the present invention.

[0028] The meanings of the labels in the attached diagram are as follows:

[0029] Substrate-1; Buffer layer-2; N-confined layer-3; N-waveguide layer-4; Quantum well active layer-5; P-waveguide layer-6; P-confined layer-7; P-contact layer-8; First trench-11; Second trench-12; Ridge waveguide-13. Detailed Implementation

[0030] The following specific examples illustrate the implementation of the present invention. The illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0031] like Figure 1 As shown, a preferred embodiment of the large-section ridge waveguide-based transverse-mode high-power semiconductor laser of the present invention includes a substrate 1, a buffer layer 2, an N-type confinement layer 3, an N-type waveguide layer 4, a quantum well active layer 5, a P-type waveguide layer 6, a P-type confinement layer 7, and a P-type contact layer 8. The substrate 1 is made of N-type doped material with a doping concentration of 2.0 × 10⁻⁶. 17 cm -3 ~2.0×10 18 cm -3 In this embodiment, the substrate 1 is preferably a GaAs substrate doped with silicon atoms, and the doping concentration is preferably 5.0 × 10⁻⁶. 17 cm -3 .

[0032] The buffer layer 2 covers the substrate 1, and the buffer layer 2 is made of N-type doped material with a doping concentration of 1×10⁻⁶. 18 cm -3 ~5×10 18 cm -3 In this embodiment, the buffer layer 2 is preferably made of GaAs material doped with silicon atoms, and the silicon atom doping concentration is preferably 1.5 × 10⁻⁶. 18 cm -3 The thickness of the buffer layer 2 is 0.2μm to 2μm, preferably 0.5μm.

[0033] The N-confinement layer 3 covers the buffer layer 2, and the N-confinement layer 3 is made of N-type doped material with a doping concentration of 0.5 × 10⁻⁶.18 cm -3 ~2x10 18 cm -3 For example, the N-limiting layer 3 can be made of a Si-doped Al x1 Ga (1-x1) As material, where 0.2≤x1≤0.6, preferably x1=0.5. The N-limiting layer 3 can also be made of a Si-doped Al x2 GaInP material, 0.1≤x2≤0.53, preferably x2=0.2. The Si-doping concentration is preferably 1.0x10 18 cm -3 The thickness of the N-limiting layer 3 is 0.2μm to 1.5μm, preferably 0.5μm.

[0034] The N-waveguide layer 4 is formed on the N-limiting layer 3, and is made of an unintentionally doped or N-type doped material with a doping concentration of 0cm -3 ~5x10 17 cm -3 For example, the N-waveguide layer 4 can be made of a Si-doped Al x3 Ga (1-x3) As material, where 0≤x3≤0.5, preferably x3=0.4. The N-waveguide layer 4 can also be made of a Si-doped GaIn x4 P material, preferably x4=0.53. The Si-doping concentration is preferably 1.0x10 17 cm -3 The thickness of the N-limiting layer 3 is 0.2μm to 1.5μm, preferably 0.5μm.

[0035] The quantum well active layer 5 is formed on the N-waveguide layer 4, and is made of an undoped material. For example, the quantum well active layer 5 can be made of an undoped In x5 GaAs y1 P material, where 0≤x5≤0.3, 0≤y1≤1; preferably x5=0.14, y1=0.72. The quantum well active layer 5 can also be made of an undoped In x6 Al x7 GaAs material, where 0≤x6≤0.3, 0≤x7≤0.6, preferably x6=0.11, x7=0.09. The thickness of the quantum well active layer 5 is 4nm to 15nm, preferably 8nm.

[0036] The P-waveguide layer 6 is formed on the quantum well active layer 5, and is made of an unintentionally doped or P-type doped material with a doping concentration of 0cm -3 ~5x10 17 cm-3 For example, the P waveguide layer 6 can employ an AlGaAs material doped with Zn atoms, C atoms, or Mg atoms, where 0 < x8 < 0.5, preferably x8 = 0.4. The P waveguide layer 6 can also employ a GaInP material doped with Zn atoms, C atoms, or Mg atoms, where 0 < x9 < 0.53, preferably x9 = 0.53. When the dopant atoms are Zn atoms, the doping concentration of the Zn atoms is preferably 1.0 x 1018cm"3. x8 (1-x8) x9 17 -3 The thickness of the P waveguide layer 6 is 0.5 μm to 2 μm, preferably 0.7 μm. The thickness of the P waveguide layer 6 is less than the thickness of the N waveguide layer 4, so that the optical field is pulled toward the N-type doped region, to reduce optical loss.

[0037] The P confinement layer 7 is formed on the P waveguide layer 6, and the P confinement layer 7 employs a P-type doped material with a doping concentration of 0.5 x 1018cm"3to 2 x 1018cm"3. 18 -3 18 -3 For example, the P confinement layer 7 can employ an AlGaAs material doped with Zn atoms, C atoms, or Mg atoms, where 0.2 < x10< 0.85, preferably x10= 0.7. The P confinement layer 7 can also employ a GaInP material doped with Zn atoms, C atoms, or Mg atoms, where 0.1 < x11< 0.53, preferably x11= 0.5. When the dopant atoms are Zn atoms, the doping concentration of the Zn atoms is preferably 1.0 x 1018cm"3. x10 (1-x10) x11 18 -3 The thickness of the P confinement layer 7 is 0.2 μm to 1.5 μm, preferably 0.5 μm.

[0038] The P contact layer 8 is formed on the P confinement layer 7, and the P contact layer 8 employs a P-type doped material with a doping concentration of 2.0 x 1018cm"3to 1.0 x 1019cm"3. 19 -3 20 -3 For example, the P contact layer 8 can employ a GaAs material doped with Zn atoms or C atoms, preferably a GaAs material doped with Zn atoms, with a doping concentration of preferably 5.0 x 1018cm"3. The P contact layer 8 can also employ a GaP material doped with Zn atoms or C atoms, preferably a GaP material doped with Zn atoms, with a doping concentration of preferably 1.0 x 1019cm"3. 19 -3 The thickness of the P contact layer 8 is 0.1 μm to 0.3 μm, preferably 0.2 μm.

[0039] ​​​​​​​​​​​​​​​The P contact layer 8 is formed with a first groove 11 and a second groove 12 penetrating the P contact layer 8 and the P confinement layer 7 and extending into the P waveguide layer 6 by etching, the etching depth g of the first groove 11 and the second groove 12 is 0.6 μm-2 μm, preferably the etching depth g=1 μm; the groove width h1 of the first groove 11 and the second groove 12 is 10 μm-50 μm; preferably the groove width h1 =20 μm. The first groove 11 and the second groove 12 are arranged in parallel, and the unetched part between the first groove 11 and the second groove 12 forms a ridge waveguide 13, the lateral ridge width h2 of the ridge waveguide 13 is 8 μm-10 μm, and the cavity length of the ridge waveguide 13 is 1 mm-5 mm.

[0040] The ridge width of the conventional ridge transverse mode ridge waveguide 13 needs to be designed to be narrow to limit the generation of multi-mode. The width of the fundamental transverse mode ridge waveguide 13 in the embodiment is increased to 8-10 μm from the conventional 3-5 μm, i.e. the waveguide width is increased by about one time, thereby greatly increasing the ridge width and the spot size to achieve the purpose of improving the output power of the laser and maintaining good beam quality. By making the thickness of the N waveguide layer 4 greater than the P waveguide layer 6, the optical field is pulled to the N doped region, thereby reducing the optical loss; by designing the groove size and selecting the material, doping atoms and concentration of each layer, the effective refractive index of the ridge structure and the effective refractive index of the two sides are less than 0.5%, thereby maintaining the fundamental transverse mode oscillation while increasing the ridge width, solving the problem that the conventional laser is difficult to simultaneously satisfy the high power and the fundamental transverse mode operation, and having the advantage of good fundamental transverse mode output beam characteristics. In addition, since the width of the ridge waveguide 13 is wider than that of the conventional ridge transverse mode ridge waveguide, the manufacturing process difficulty can also be reduced.

[0041] Finally, it should be pointed out that the above embodiments are only used to illustrate the technical solutions of the present application but not limit the present application, although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or replaced equivalently without departing from the purpose and scope of the present technical solutions, which should be covered in the scope of the claims of the present application.

Claims

1. A large cross-section ridge waveguide base transverse mode high power semiconductor laser, characterized by: The substrate is doped with an N-type material. A buffer layer is formed on the substrate, which is doped with an N-type material. An N-limiting layer is formed on the buffer layer, which is doped with an N-type AlGaAs material or an AlGaInP material, and has a thickness of 0.2-1.5 μm. An N-waveguide layer is formed on the N-limiting layer, which is doped with an unintentional or N-type material. A quantum well active layer is formed on the N-waveguide layer, which is doped with an InGaAsP material or an InAlGaAs material. A P-waveguide layer is formed on the quantum well active layer, which is doped with an unintentional or P-type material, and has a thickness less than that of the N-waveguide layer. A P-limiting layer is formed on the P-waveguide layer, which is doped with a P-type AlGaAs material or an AlGaInP material, and has a thickness of 0.2-1.5 μm. A P-contact layer is formed on the P-limiting layer, which is doped with a P-type material. The P-contact layer is etched to form a first groove and a second groove extending through the P-contact layer and the P-limiting layer and into the P-waveguide layer, with an etching depth of 0.6-1 μm, and the first groove and the second groove are arranged in parallel, and a ridge waveguide is formed in the unetched portion between the first groove and the second groove; the lateral ridge width of the ridge waveguide is 8-10 μm, and the cavity length of the ridge waveguide is 1-5 mm. The groove width of the first groove and the second groove is 10-50 μm. The thickness of the quantum well active layer is 4-15 nm.

2. The large cross-section ridge waveguide base transverse mode high power semiconductor laser of claim 1, wherein: ​ 3. The large cross-section ridge waveguide base lateral mode high power semiconductor laser of claim 1 or 2, characterized in that: The substrate is an N-type doped GaAs substrate, the doping atom is a silicon atom, the doping concentration is 2.0 x 10 17 cm -3 ~ 2.0 x 10 18 cm -3 .

4. The large cross-section ridge waveguide base lateral mode high power semiconductor laser of claim 1 or 2, characterized in that: The buffer layer is N-type doped GaAs material, the doping atom is silicon atom, the doping concentration is 1×10 18 cm -3 ~5×10 18 cm -3 ; the thickness of the buffer layer is 0.2μm~2μm.

5. The large cross-section ridge waveguide base lateral mode high power semiconductor laser of claim 1 or 2, characterized in that: The doping atoms of the N-limiting layer are silicon atoms, and the doping concentration is 0.5x10 18 cm -3 ~2x10 18 cm -3 .

6. The large cross-section ridge waveguide base lateral mode high power semiconductor laser of claim 1 or 2, characterized in that: The N waveguide layer is an N-doped AlGaAs material or GaInP material, the doping atom is silicon atom, the doping concentration is 0cm -3 ~5x10 17 cm -3 ; the thickness of the N waveguide layer is 0.5μm~4μm.

7. The large cross-section ridge waveguide base lateral mode high power semiconductor laser of claim 1 or 2, characterized in that: ​ 8. The large cross-section ridge waveguide base lateral mode high power semiconductor laser of claim 1 or 2, characterized in that: The P waveguide layer is a P-type doped AlGaAs material or GaInP material, the doping atoms are Zn atoms, C atoms or Mg atoms, the doping concentration is 0cm -3 ~5x10 17 cm -3 The thickness of the P waveguide layer is 0.5μm~2μm.

9. The large cross-section ridge waveguide base lateral mode high power semiconductor laser of claim 1 or 2, characterized in that: The doping atoms of the P-limiting layer are Zn atoms, C atoms or Mg atoms, and the doping concentration is 0.5x10 18 cm -3 ~2x10 18 cm -3 .

10. The large cross-section ridge waveguide base lateral mode high power semiconductor laser of claim 1 or 2, characterized in that: The P contact layer is a P-type doped GaAs material, the doping atoms are Zn atoms or C atoms, the doping concentration is 2×10 19 cm -3 ~1×10 20 cm -3 , and the thickness of the P contact layer is 0.1 μm~0.3 μm.

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