Conical semiconductor laser based on lateral aperiodic slot structure

Abstract

A tapered semiconductor laser based on a lateral aperiodic slot structure disclosed by the present invention comprises a semiconductor laser main body structure, the semiconductor laser main body structure comprises a P-type region, an active region and an N-type region which are sequentially arranged from top to bottom, and the P-type region comprises a P-type contact layer, a P-type limiting layer and a P-type waveguide layer. The N-type region comprises an N-type waveguide layer, an N-type limiting layer and a substrate; the semiconductor laser further comprises a conical main waveguide and lateral non-periodic slot structures, the lateral non-periodic slot structures are located on the face, provided with the P-type area, of the semiconductor laser body structure, the lateral non-periodic slot structures are arranged on the two sides of the conical main waveguide, and each lateral non-periodic slot structure comprises a plurality of slots which are sequentially arranged in the lateral direction at different intervals. And loss microstructures are arranged between the slots. According to the conical semiconductor laser provided by the invention, the laser output power can be improved while the number of lateral modes is limited, so that high-brightness laser output is realized, and the conical semiconductor laser has good comprehensive performance.

Description

Technical Field

[0001] The invention relates to a tapered semiconductor laser based on a lateral non-periodic slot structure, belonging to the technical field of semiconductor lasers. Background Art

[0002] Semiconductor lasers are devices that use certain semiconductor materials as their working medium to generate laser light. Their operating principle is to achieve a population inversion of non-equilibrium carriers between the semiconductor's energy bands (conduction band and valence band), or between the semiconductor's energy bands and the energy levels of impurities (acceptor or donor) through a specific excitation method. When a large number of electrons in this population inversion state recombine with holes, stimulated emission occurs.

[0003] Semiconductor lasers offer numerous advantages, including light weight, compact size, low cost, and ease of integration. Currently, they are widely used in a wide range of fields, including materials processing, communications, military, and medical applications. However, these applications, including pump sources for solid-state and fiber lasers, laser scalpels, laser weapons, metal cutting and welding, and laser displays, all place high demands on laser brightness. Achieving high laser brightness requires both high output power and high beam quality.

[0004] Conventional wide-ridge waveguide lasers can achieve high single-tube output power and power conversion efficiency, but due to their relatively wide output aperture, they are prone to lateral multimode generation, resulting in poor beam quality. Conventional narrow-ridge waveguide lasers can achieve lateral near-diffraction-limited output, but their power is low due to their small output aperture and gain volume.

[0005] Therefore, it is necessary to propose a tapered semiconductor laser that can increase the laser output power while limiting the number of lateral modes, thereby achieving high-brightness laser output and having good comprehensive performance. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to address the above shortcomings and provide a tapered semiconductor laser based on a lateral non-periodic slot structure, which can increase the laser output power while limiting the number of lateral modes, thereby achieving high-brightness laser output and having good comprehensive performance.

[0007] In order to solve the above technical problems, the present invention adopts the following technical solutions: A tapered semiconductor laser based on a lateral non-periodic slot structure comprises a semiconductor laser main structure, wherein the semiconductor laser main structure comprises a P-type region, an active region and an N-type region sequentially arranged from top to bottom, wherein the P-type region comprises a P-type contact layer, a P-type confinement layer and a P-type waveguide layer, and the N-type region comprises an N-type waveguide layer, an N-type confinement layer and a substrate; and further comprises a tapered main waveguide and a lateral non-periodic slot structure, wherein the lateral non-periodic slot structure is located on a side of the semiconductor laser main structure where the P-type region is provided, and the lateral non-periodic slot structure is arranged on both sides of the tapered main waveguide, and comprises a plurality of slots sequentially arranged laterally at different spacings, and lossy microstructures are arranged between the slots.

[0008] Furthermore, the tapered main waveguide includes a ridge region for mode confinement and a tapered region for power amplification.

[0009] Furthermore, the depth of the lateral non-periodic slot structure is greater than the sum of the thicknesses of the P-type contact layer and the P-type confinement layer, and the bottom of the lateral non-periodic slot structure is located in the P-type waveguide layer.

[0010] Furthermore, the slot width of the lateral non-periodic slot structure is smaller than the action range of the evanescent field of the waveguide guided mode on both sides, and the distances between adjacent slots are different.

[0011] Furthermore, the lateral non-periodic slot structure is arranged at one end close to the light-emitting surface of the device, and its length along the light-emitting direction is less than or equal to the length of the tapered main waveguide.

[0012] Furthermore, the lateral non-periodic slot structures are distributed in a mirror-symmetrical or mirror-asymmetrical manner on both sides of the tapered main waveguide.

[0013] Furthermore, the lossy microstructure is a randomly distributed high-order surface loss slot, or ion implantation is used to increase light propagation loss, or both.

[0014] Furthermore, the tapered main waveguide has electric injection, while the lateral non-periodic slot structure does not have electric injection.

[0015] Furthermore, a DBR grating is provided on the narrow ridge of the tapered main waveguide.

[0016] Furthermore, spoiler grooves are provided on both sides of the connection between the narrow ridge of the tapered main waveguide and the tapered area.

[0017] After adopting the above technical solution, the present invention has the following advantages compared with the prior art: 1. The lateral non-periodic slot structure is coupled with the lateral high-order modes of the main waveguide, reducing the confinement factor of the lateral high-order modes and allowing the setting of a wider tapered main waveguide. Compared with the traditional tapered structure, while limiting the number of lateral modes, it also increases the laser output power, thereby achieving higher brightness laser output.

[0018] 2. Compared with supersymmetric and PT-symmetric waveguide designs, the lateral non-periodic slot structure allows operation over a wider current range. Under high currents, the supersymmetric waveguide experiences a mismatch in mode propagation constants due to temperature rise, and the main waveguide gain of the PT-symmetric waveguide is greater than the loss of the side waveguide. The lateral non-periodic slot structure can overcome these problems and still suppress lateral high-order modes under high currents.

[0019] The present invention is described in detail below with reference to the accompanying drawings and embodiments. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 is a schematic structural diagram of the tapered semiconductor laser of Example 1; Figure 2 is a top view of the electric field amplitude distribution of the reflected and incident fields of the tapered semiconductor laser in Example 1; Figure 3 1 is a graph showing the relationship between the beam diameter of the tapered semiconductor laser in the horizontal and vertical directions and the position of the tapered semiconductor laser in Example 1; Figure 4 is a schematic structural diagram of a tapered semiconductor laser according to Example 2; Figure 5 It is a schematic structural diagram of the tapered semiconductor laser of Example 3.

[0021] In the figure, 1-P-type region, 2-active region, 3-N-type region, 4-tapered main waveguide, 5-lateral non-periodic slot structure, 6-loss microstructure, 7-DBR grating, 8-spoiler groove. DETAILED DESCRIPTION

[0022] In order to have a clearer understanding of the technical features, purposes and effects of the present invention, specific embodiments of the present invention are now described with reference to the accompanying drawings.

[0023] Example 1 like Figure 1 As shown, the present invention provides a tapered semiconductor laser based on a lateral non-periodic slot structure, wherein the light emitting direction is the positive direction of the x-axis and the lateral direction is the y-axis direction.

[0024] The conical semiconductor laser includes a semiconductor laser main structure, which includes a P-type region 1, an active region 2 and an N-type region 3 arranged in sequence from top to bottom, the P-type region 1 includes a P-type contact layer, a P-type confinement layer and a P-type waveguide layer, and the N-type region 3 includes an N-type waveguide layer, an N-type confinement layer and a substrate; and further includes a conical main waveguide 4 and a lateral non-periodic slot structure 5. The lateral non-periodic slot structure 5 is located on a side of the semiconductor laser main structure where the P-type region 1 is provided. The lateral non-periodic slot structure 5 is arranged on both sides of the conical main waveguide 4. The lateral non-periodic slot structure 5 includes a plurality of slots with different spacing distances arranged in sequence along the lateral direction, and a lossy microstructure 6 is arranged between the slots.

[0025] The tapered main waveguide 4 includes a ridge region for mode confinement and a tapered region for power amplification.

[0026] The depth of the lateral non-periodic slot structure 5 is greater than the sum of the thicknesses of the P-type contact layer and the P-type confinement layer, and the bottom of the lateral non-periodic slot structure 5 is located in the P-type waveguide layer.

[0027] The width of the lateral non-periodic slot structure 5 is smaller than the action range of the evanescent field of the waveguide guided mode on both sides, and the distances between adjacent slots are different.

[0028] The lateral non-periodic slot structure 5 is arranged at one end close to the light-emitting surface of the device, and its length along the light-emitting direction is less than or equal to the length of the tapered main waveguide 4 .

[0029] The lateral non-periodic slot structures 5 are distributed on both sides of the tapered main waveguide 4 in a mirror-symmetrical or mirror-asymmetrical manner.

[0030] The lossy microstructure 6 is a randomly distributed high-order surface loss slot, or uses ion implantation to increase light propagation loss, or both.

[0031] Electric injection exists in the tapered main waveguide 4 , but no electric injection exists in the lateral non-periodic slot structure 5 .

[0032] Figure 2 Shown is a top-down view of the electric field amplitude distribution of the reflected (left) and incident (right) fields of the first three lateral modes of the 980nm wavelength laser in this simulation example. The total cavity length of the device is 4 mm, and the slot width in the lateral non-periodic slot structure is 1 μm. The results show that the lateral high-order modes are partially coupled into the lateral non-periodic slot structure, reducing the mode competition ability of the lateral high-order modes and thus improving the beam quality of the semiconductor laser.

[0033] Figure 3Figure 2 shows the relationship between the horizontal and vertical beam diameters (second-order moment standard) of the 980 nm laser of this embodiment, measured at 5°C temperature and 4.3 A continuous wave current (4.5 W laser output) versus position. This device uses a COS flip-chip package. The emitted light is collimated by an aspheric lens and the beam direction is adjusted by a pair of reflectors so that the light is vertically incident on the BeamSquared tester produced by Ophir. By fitting the data in this figure, the beam quality M under the second-order moment standard can be obtained. 2 is 3.3, and the brightness of the device at the second-order moment level is obtained to be 144 MW / cm2 / Sr.

[0034] Example 2 like Figure 4 As shown, the present invention provides a tapered semiconductor laser based on a lateral non-periodic slot structure. The difference between Example 2 and Example 1 is that: In the second embodiment, a DBR grating 7 is provided on the narrow ridge of the tapered main waveguide 4 .

[0035] The seed light is first limited in the number of lateral modes by the ridge region. After the longitudinal mode is selected by the DBR grating 7, it undergoes two optical amplifications and couples with the lateral non-periodic slot structure 5 to further suppress the high-order modes, ultimately obtaining a high-power output with high beam quality.

[0036] Example 3 like Figure 5 As shown, the present invention provides a tapered semiconductor laser based on a lateral non-periodic slot structure. The difference between Example 3 and Example 1 is that: In Example 3, spoiler grooves 8 are provided on both sides of the connection between the narrow ridge and the tapered area of the tapered main waveguide 4 to prevent the reflected light from the front cavity surface from being amplified by the tapered area and then returning to the two sides of the narrow ridge.

[0037] The foregoing is an example of the best mode of carrying out the present invention. Any portion not described in detail herein is common knowledge within the skill of one of ordinary skill in the art. The scope of protection of the present invention is determined by the claims. Any equivalent transformation based on the technical teachings of the present invention is also within the scope of protection of the present invention.

Claims

1. A conical semiconductor laser based on a lateral non-periodic slot structure, comprising a semiconductor laser main structure, wherein the semiconductor laser main structure comprises a P-type region (1), an active region (2) and an N-type region (3) arranged in sequence from top to bottom, wherein the P-type region (1) comprises a P-type contact layer, a P-type confinement layer and a P-type waveguide layer, and the N-type region (3) comprises an N-type waveguide layer, an N-type confinement layer and a substrate, and wherein: The invention also includes a tapered main waveguide (4) and a lateral non-periodic slot structure (5), wherein the lateral non-periodic slot structure (5) is located on a side of the semiconductor laser main structure provided with a P-type region (1), and the lateral non-periodic slot structure (5) is arranged on both sides of the tapered main waveguide (4). The lateral non-periodic slot structure (5) includes a plurality of slots with different spacing distances arranged in sequence along the lateral direction, and loss microstructures (6) are arranged between the slots.

2. The tapered semiconductor laser based on a lateral non-periodic slot structure according to claim 1, characterized in that: The tapered main waveguide (4) includes a ridge region for mode confinement and a tapered region for power amplification.

3. The tapered semiconductor laser based on a lateral non-periodic slot structure according to claim 1, characterized in that: The depth of the lateral non-periodic slot structure (5) is greater than the sum of the thicknesses of the P-type contact layer and the P-type confinement layer, and the bottom of the lateral non-periodic slot structure (5) is located in the P-type waveguide layer.

4. The tapered semiconductor laser based on a lateral non-periodic slot structure according to claim 3, characterized in that: The slot width of the lateral non-periodic slot structure (5) is smaller than the action range of the evanescent field of the waveguide guided mode on both sides, and the distances between adjacent slots are different.

5. The tapered semiconductor laser based on a lateral non-periodic slot structure according to claim 3, characterized in that: The lateral non-periodic slot structure (5) is arranged at one end close to the light-emitting surface of the device, and its length along the light-emitting direction is less than or equal to the length of the tapered main waveguide (4).

6. The tapered semiconductor laser based on a lateral non-periodic slot structure according to claim 3, characterized in that: The lateral non-periodic slot structures (5) are distributed on both sides of the tapered main waveguide (4) in a mirror-symmetrical or mirror-asymmetrical manner.

7. The tapered semiconductor laser based on a lateral non-periodic slot structure according to claim 1, characterized in that: The loss microstructure (6) is a randomly distributed high-order surface loss slot, or uses ion implantation to increase light propagation loss, or both.

8. The tapered semiconductor laser based on a lateral non-periodic slot structure according to claim 1, characterized in that: The tapered main waveguide (4) has electric injection, while the lateral non-periodic slot structure (5) does not have electric injection.

9. The tapered semiconductor laser based on a lateral non-periodic slot structure according to claim 1, characterized in that: A DBR grating (7) is provided on the narrow ridge of the tapered main waveguide (4).

10. The tapered semiconductor laser based on a lateral non-periodic slot structure according to claim 1, characterized in that: Disturbing grooves (8) are provided on both sides of the connection between the narrow ridge and the tapered area of the tapered main waveguide (4).

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