Laser based on annular plane medium grating with two different grating constants

Abstract

The invention relates to the technical field of semiconductor lasers, in particular to a laser based on two annular planar dielectric gratings with different grating constants. The laser quantum well gain layer is arranged on the upper end surface of the substrate; the annular plane medium grating is arranged on an upper waveguide layer of the laser quantum well gain layer; the upper cladding is constructed above the annular planar dielectric grating through a semiconductor secondary epitaxy method; a top positive electrode; a bottom negative electrode; the AR anti-reflection interface is arranged at the laser output part of the annular plane medium grating, and the light output opening angle phi of the laser output part of the annular plane medium grating is larger than 0 degree and smaller than or equal to 360 degrees; and the HR high-reflection interface is arranged at a non-laser output part of the annular plane medium grating. The invention has the following beneficial effects: 1, all-solid-state large-angle output is realized; 2, high power output and high gain efficiency; 3, narrow linewidth characteristic and high wavelength purity; and 4, the structure is compact and the cost is low.

Description

Technical Field

[0001] This invention relates to the field of semiconductor laser technology, specifically to a laser based on annular planar dielectric gratings with two different grating constants. Background Technology

[0002] A laser is a device that converts electrical, chemical, or optical energy into light energy. Its core principle is stimulated emission. When the laser medium (solid, gas, liquid, or semiconductor) is activated to a high-energy state, the injected energy induces stimulated emission, producing light with the same frequency and phase as the initial light wave. Through the feedback mechanism of the optical resonant cavity, the light intensity is increased by repeated reflections, ultimately forming a laser beam. Existing lasers have the following technical limitations: 1. Narrow-angle linear laser: The effective gain region is limited to a narrow linear range, the output power is low, and the output angle is fixed and narrow (usually <30°). Additional optical or mechanical structures are required to extend the angle, which increases the system complexity and cost. 2. Mechanical scanning large-angle laser: Although it can achieve a large angle coverage, it relies on mechanical components such as motors and galvanometers, and has problems such as slow response, short life (mean time between failures < 10,000 hours), poor stability due to vibration interference, and cannot achieve omnidirectional output without mechanical transmission.

[0003] As can be seen from the above, current semiconductor lasers cannot meet the integrated requirements of "all solid-state + large angle (including all directions) + high power + narrow linewidth". In addition, existing lasers generally have a wide linewidth (>10nm), which makes them susceptible to environmental interference in high-precision applications, requiring additional filtering modules, which further increases the size and cost. Summary of the Invention

[0004] The purpose of this invention is to solve the problems mentioned in the background art. This invention provides the following technical solution: a laser based on two annular planar dielectric gratings with different grating constants, comprising: Substrate; A laser quantum well gain layer is disposed on the upper end face of the substrate; An annular planar dielectric grating is disposed on the upper waveguide layer of the laser quantum well gain layer. The annular planar dielectric grating includes a first annular planar dielectric grating and a second annular planar dielectric grating. The grating constant Λ1 of the first annular planar dielectric grating is not equal to the grating constant Λ2 of the second annular planar dielectric grating. The upper cladding layer is constructed above the annular planar dielectric grating using a semiconductor secondary epitaxy method; The top positive electrode is disposed on the upper end surface of the upper cladding; The bottom negative electrode is disposed on the lower end surface of the substrate; An AR anti-reflective interface is disposed in the laser output section of the annular planar dielectric grating, wherein the light output opening angle φ of the laser output section of the annular planar dielectric grating is in the range of 0°<φ≤360°; The HR high-reflectivity interface is disposed in the non-laser output section of the annular planar dielectric grating.

[0005] As a preferred embodiment of the above technical solution, the HR high-reflectivity interface is one of a metal film, a dielectric film, and a coating.

[0006] This invention provides a laser based on two annular planar dielectric gratings with different grating constants, which has the following advantages: 1. All-solid-state large-angle output, up to 360° in all directions: No mechanical transmission components such as motors and galvanometers are required. The output angle can be flexibly set by adjusting the coverage angle of the HR layer, achieving up to 360° all-round coverage. There is no mechanical wear, and the mean time between failures is increased to more than 50,000 hours. 2. High power output and high gain efficiency: The effective gain area of ​​the butterfly structure is 5-10 times that of traditional narrow straight lasers, and the output power is increased to 10-50W to meet the needs of high power scenarios; 3. Narrow linewidth characteristics and high wavelength purity: The annular planar dielectric grating can compress the laser linewidth to 0.1-1nm, which is far superior to traditional lasers (10-50nm), eliminating the need for additional filtering modules and reducing the system volume by more than 30%; 4. Compact structure and low cost: It adopts a layered stacked integrated design and is mass-produced through mature semiconductor processes. No additional optical or mechanical structural adjustments are required, reducing production costs by 20-40%. Attached Figure Description

[0007] Figure 1 This is a schematic diagram showing the positional relationship between the annular planar dielectric grating and the HR high-reflectivity interface in this invention; Figure 2 This is a schematic diagram of the front structure of the present invention.

[0008] In the figure: 1. Substrate; 2. Laser quantum well gain layer; 3. Annular planar dielectric grating; 31. First annular planar dielectric grating; 32. Second annular planar dielectric grating; 4. HR high reflectivity interface; 5. Upper cladding; 6. Top positive electrode; 7. Bottom negative electrode; 8. AR antireflective interface. Detailed Implementation

[0009] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0010] A laser based on two annular planar dielectric gratings with different grating constants, comprising: Substrate 1 is made of III-V group semiconductor materials (GaAs, InP, etc.), with a thickness of 100-300μm and a surface roughness Ra≤0.5nm, as a support substrate to reduce light loss and ensure lattice matching with the upper quantum well layer. The laser quantum well gain layer 2 is disposed on the upper surface of the substrate 1. It adopts a multi-quantum well structure (such as InGaAs / GaAs, InGaAsP / InP), which is a multi-layer structure with 3-5 layers and each layer is 5-10nm thick. It is used to generate laser gain and is the core of the light source. An annular planar dielectric grating 3 is disposed on the upper waveguide layer of the laser quantum well gain layer 2. The annular structure ensures uniformity of filtering at all angles. The annular planar dielectric grating 3 includes a first annular planar dielectric grating 31 and a second annular planar dielectric grating 32. The grating constant Λ1 of the first annular planar dielectric grating 31 is not equal to the grating constant Λ2 of the second annular planar dielectric grating 32. The upper cladding layer 5 is constructed above the annular planar dielectric grating 3 by semiconductor secondary epitaxy. It is made of high-transmittance semiconductor material (AlGaAs, InGaP, etc.) and has a thickness of 50-100μm. It is used to protect the grating layer and reduce laser surface reflection loss. The top positive electrode 6 is disposed on the upper end face of the upper cladding 5 to provide positive current injection and form a symmetrical circuit with the negative electrode; The bottom negative electrode 7 is disposed on the lower end face of the substrate 1 to provide reverse current injection and ensure that the current is uniformly distributed to the quantum well layer. An AR anti-reflection interface 8 is disposed on the laser output section of the annular planar dielectric grating 3. The range of the light output aperture angle φ of the laser output section of the annular planar dielectric grating 3 is 0°<φ≤360°, which is used to reduce natural reflection at the output end face and improve the monochromaticity of the laser wavelength. By adjusting the AR coverage angle, the light output aperture angle φ can be flexibly controlled. When φ=360°, omnidirectional laser output is achieved. The HR high-reflectivity interface 4 is disposed in the non-laser output section of the annular planar dielectric grating 3 to reflect laser light from the non-output direction back to the laser quantum well gain layer 2, thereby improving power and efficiency; and by cooperating with the AR anti-reflection interface 8, the light output aperture angle φ can be flexibly controlled.

[0011] As a preferred embodiment of the above technical solution, the annular planar dielectric grating 3 is one of an etched geometric grating, a doped element-modified refractive index grating, and a metal grating.

[0012] As a preferred embodiment of the above technical solution, the HR high-reflectivity interface 4 is one of a metal film, a dielectric film, and a coating.

[0013] Example 1: 1550nm all-solid-state omnidirectional (360°) butterfly laser (for omnidirectional laser illumination) 1. Component parameter design Substrate 1: InP substrate, thickness 250μm, surface roughness Ra=0.2nm; Laser quantum well gain layer 2: InGaAsP / InP multiple quantum wells (4 layers, each layer thickness 8nm), emission wavelength 1550nm; 3. Annular planar dielectric grating; Upper cladding 5: AlGaAs material, 50 μm thick; HR High Reflectivity Interface 4: SiO2 / ZrO2 dielectric reflective film (reflectivity 99.8%), coverage angle 0° (i.e., light output aperture angle φ=360°); Bottom negative electrode 7: Cu-Au alloy; Top positive electrode 6: ITO.

[0014] 2. Performance Indicators Output power 15W, laser linewidth 0.3nm, output angle 360°, operating temperature -40℃-85℃, mean time between failures 60,000 hours.

[0015] Example 2: 905nm all-solid-state large-angle (180°) butterfly laser (for lidar) 1. Component parameter design: Substrate 1: GaAs substrate, thickness 200μm, surface roughness Ra=0.3nm; Laser quantum well gain layer 2: InGaAs / GaAs multiple quantum wells (3 layers, each layer thickness 7nm), emission wavelength 905nm; 3. Annular planar dielectric grating; Upper cladding 5: InGaP material, 100μm thick; HR High Reflectivity Interface 4: Au film (95% reflectivity), coverage angle 180° (i.e., opening angle φ=180°). Bottom negative electrode 7: Au; Top positive electrode 6: AZO.

[0016] 2. Performance Indicators: Output power 10W, laser linewidth 0.5nm, output angle 180°, signal-to-noise ratio ≥28dB at 150 meters, operating temperature -30℃ to 80℃, mean time between failures 55,000 hours.

[0017] The working principle of this invention is as follows: 1. Current injection: An external power source injects current into the laser quantum well gain layer 2 through the bottom negative electrode 7 and the top positive electrode 6. Electrons jump from the conduction band to the valence band and recombine with holes to generate spontaneous emission light. 2. Gain amplification: Spontaneous emission light propagates within the butterfly-shaped gain region, generating more stimulated emission light of the same frequency and phase, thus forming a high-power laser gain (the butterfly-shaped structure gain region is 5-10 times that of a traditional narrow straight-strip laser). 3. Narrow linewidth filtering: The annular planar dielectric grating 3 performs wavelength screening on the gain light, allowing only specific wavelengths of light to pass through, filtering out stray light, and achieving narrow linewidth output; 4. Large angle (including all-round) output: The HR high reflectivity interface 4 reflects the laser from the non-output direction back to the laser quantum well gain layer 2, further improving the power; by adjusting the coverage angle of the HR high reflectivity interface 4, the light output opening angle φ (0<φ≤360°) can be flexibly controlled. When φ=360°, there is no obstruction in the output direction, achieving all-round laser coverage, and no mechanical transmission components are required throughout the process.

[0018] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A laser based on a ring-shaped planar dielectric grating with two different grating constants, characterized in that: Comprise: a substrate (1); a laser quantum well gain layer (2) disposed on the upper end surface of the substrate (1); a ring-shaped planar dielectric grating (3) disposed on the upper waveguide layer of the laser quantum well gain layer (2), the ring-shaped planar dielectric grating (3) comprising a first ring-shaped planar dielectric grating (31) and a second ring-shaped planar dielectric grating (32), the grating constant Λ1 of the first ring-shaped planar dielectric grating (31) ≠ the grating constant Λ2 of the second ring-shaped planar dielectric grating (32); an upper cladding layer (5) constructed above the ring-shaped planar dielectric grating (3) by a semiconductor secondary epitaxy method; a top positive electrode (6) disposed on the upper end surface of the upper cladding layer (5); a bottom negative electrode (7) disposed on the lower end surface of the substrate (1); an AR anti-reflection interface (8) disposed at the laser output portion of the ring-shaped planar dielectric grating (3), the light output opening angle φ of the laser output portion of the ring-shaped planar dielectric grating (3) ranging from 0° < φ ≤ 360°; an HR high-reflection interface (4) disposed at the non-laser output portion of the ring-shaped planar dielectric grating (3).

2. A laser based on two different grating constant annular planar dielectric grating according to claim 1, characterized in that: The HR high-reflection interface (4) is a metal film.

3. A laser based on two different grating constant annular planar dielectric grating according to claim 1, characterized in that: The HR high-reflection interface (4) is a dielectric film.

4. A laser based on two different grating constant annular planar dielectric grating according to claim 1, characterized in that: The HR high-reflection interface (4) is a coating.

Images