Semiconductor laser

Abstract

The present disclosure provides a semiconductor laser, which includes a buffer layer, a lower confinement layer, a lower waveguide layer, an active region, an upper waveguide layer, an upper confinement layer, a cap layer, a top electrode sequentially grown on the surface of a substrate, and a bottom electrode formed on the back surface of the substrate. The upper confinement layer, the cap layer and the top electrode form a ridge, and a mode regulation array structure is arranged on the ridge. The mode regulation array structure includes channels and an arrow structure array. The channels are formed on both sides of the ridge. The arrow structure array includes a plurality of arrow structure units, and each arrow structure unit includes at least one arrow. Among them, the arrow structure units in the arrow structure array are formed at the peak positions of the N-1 order mode of the lateral light field distribution of the semiconductor laser, where N is an integer greater than or equal to 2.

Description

Technical Field

[0001] The present disclosure relates to the field of semiconductor laser technology, and more particularly, to a semiconductor laser. Background Art

[0002] Semiconductor lasers have the advantages of small size, light weight, high efficiency, etc., and have important applications in many fields such as material processing, gas detection, medical devices, and optoelectronic countermeasures. With the expansion of application fields, high power and high beam quality have become the basic requirements for semiconductor lasers.

[0003] In the process of implementing the concept of the present disclosure, the inventors have found at least the following problems in the prior art: Traditional wide-area semiconductor lasers have the advantage of high power, but the lateral ridge width is much larger than the lasing wavelength, so there will be a large number of optical modes. Self-focusing, thermal lensing, beam filamentation effects, etc. make the divergence angle of the device large, which limits the beam quality of the entire device. Summary of the Invention

[0004] In view of this, an embodiment of the present disclosure provides a semiconductor laser.

[0005] According to one aspect of the present disclosure, there is provided a semiconductor laser, including a buffer layer, a lower confinement layer, a lower waveguide layer, an active region, an upper waveguide layer, an upper confinement layer, a cap layer, a top electrode sequentially grown on the surface of a substrate, and a bottom electrode formed on the back surface of the substrate. The upper confinement layer, the cap layer, and the top electrode form a ridge, and a mode regulation array structure is provided on the ridge. The mode regulation array structure includes channels and an arrow structure array. The channels are formed on both sides of the ridge. The arrow structure array includes a plurality of arrow structure units, and each arrow structure unit includes at least one arrow. Among them, the arrow structure units in the arrow structure array are formed at the peak positions of the N-1 order mode of the lateral optical field distribution of the semiconductor laser, where N is an integer greater than or equal to 2.

[0006] According to an embodiment of the present disclosure, in each arrow structure array, the number of arrows in the arrow structure unit increases from the center of the ridge to both sides.

[0007] According to an embodiment of the present disclosure, the direction of the arrow in the arrow structure unit is consistent with the change of the peak position of the N-1 order mode when the injection current increases.

[0008] According to an embodiment of the present disclosure, the width of the arrow tail of the arrow is 1-10 μm, and the width of the arrow head is 1-5 μm.

[0009] According to an embodiment of the present disclosure, the arrow structure array is formed on both sides of the ridge near the front cavity surface and the rear cavity surface of the semiconductor laser, or formed in the middle of the ridge, or formed on one side near the front cavity surface of the semiconductor laser, or formed on the upper surface of the entire ridge.

[0010] According to an embodiment of the present disclosure, the etching depth of the ridge is between the upper surface of the upper confinement layer and the lower surface of the upper waveguide layer.

[0011] According to an embodiment of the present disclosure, the etching depth of the ridge is 1-3 μm.

[0012] According to an embodiment of the present disclosure, the etching depth of the mode regulation structure is between the upper surface and the lower surface of the upper confinement layer.

[0013] According to an embodiment of the present disclosure, the etching depth of the mode regulation structure is 1-3 μm.

[0014] According to an embodiment of the present disclosure, the ratio of the etched part to the unetched part of the mode regulation structure is 2:8 - 8:2.

[0015] According to an embodiment of the present disclosure, the ratio of the etched part to the unetched part of the mode regulation structure is 6:4.

[0016] According to an embodiment of the present disclosure, the active region includes K1 quantum wells and K2 barrier layers, where K1 is an integer greater than or equal to 1, and K2 is an integer greater than or equal to 0.

[0017] According to an embodiment of the present disclosure, the material used for the substrate is a group III-V compound.

[0018] According to an embodiment of the present disclosure, the material used for the substrate is GaSb.

[0019] According to an embodiment of the present disclosure, the width of the channel is 1-5 μm.

[0020] As can be seen from the above technical solutions, the beneficial effects of the semiconductor laser provided by the present disclosure are as follows:

[0021] 1. For the semiconductor laser provided by the present disclosure, by providing a mode regulation array structure including a channel and an arrow structure array on the surface of the ridge, wherein the two-side channels can effectively suppress lateral carrier accumulation, and the arrow array structure can gradiently suppress high-order modes, increasing the advantage of low-order modes in mode competition, making the energy distribution more concentrated and the far-field divergence angle lower;

[0022] 2. For the semiconductor laser provided by the present disclosure, by making the number of arrows in the arrow structure unit increase from the center of the ridge to both sides, the loss of high-order modes can be further increased;

[0023] 3. The semiconductor laser provided by the present disclosure realizes compensation for the thermal lens effect and improvement of the deterioration of the lateral divergence angle under high current injection by making the direction of the arrow consistent with the change in the peak position of the high mode when the injection current increases;

[0024] 4. The semiconductor laser provided by the present disclosure adopts a mode control array structure, which is beneficial to heat dissipation, can improve the thermal saturation phenomenon, and realizes the maintenance or further increase of the output power.

[0025] 5. The semiconductor laser provided by the present disclosure has a simple manufacturing process and is compatible with large-scale production. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Through the following description of the embodiments of the present disclosure with reference to the accompanying drawings, the above and other objects, features and advantages of the present disclosure will become clearer. In the drawings:

[0027] Figure 1 Schematically shows a schematic diagram of the semiconductor laser of the embodiment of the present disclosure;

[0028] Figure 2 Schematically shows a top view of the semiconductor laser of Embodiment 1 of the present disclosure;

[0029] Figure 3 Schematically shows the lateral far-field pattern of the semiconductor laser of Embodiment 1 of the present disclosure. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0030] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. However, it should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present disclosure. In the following detailed description, for the sake of explanation, many specific details are set forth to provide a comprehensive understanding of the embodiments of the present disclosure. However, obviously, one or more embodiments can also be implemented without these specific details. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present disclosure.

[0031] The terms used herein are merely for describing specific embodiments and are not intended to limit the present disclosure. The terms "including", "comprising" and the like used herein indicate the presence of the described features, steps, operations and / or components, but do not exclude the presence or addition of one or more other features, steps, operations or components.

[0032] In the case of using expressions such as "at least one of A, B, or C, etc.", generally, it should be interpreted according to the meaning that those skilled in the art usually understand this expression (for example, "a system having at least one of A, B, or C" should include but not be limited to a system having only A, only B, only C, having A and B, having A and C, having B and C, and / or having A, B, and C, etc.). The terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the said features.

[0033] Traditional wide-area semiconductor lasers have the advantage of high power. However, since the lateral ridge width is much larger than the lasing wavelength, there will be a large number of optical modes. Self-focusing, thermal lensing, beam filamentation effects, etc. cause a large divergence angle of the device, with a multi-lobe lateral far field, resulting in low coupling efficiency during application and limiting the beam quality of the entire device. There are various existing solutions to improve the lateral divergence angle, including the external cavity method, tapered waveguides, and curved waveguides, etc. The external cavity method and tapered waveguides can achieve high-order mode filtering, but the external cavity method will cause large optical losses and requires fine optical path adjustment. The tapered waveguide has high astigmatism, and the subsequent optical design is complex. The narrow ridge part used for mode filtering will limit the further increase of power. The curved waveguide increases the high-order mode loss to improve the beam quality, but at the same time increases the threshold current.

[0034] In view of the above problems, embodiments of the present disclosure provide a semiconductor laser, including a buffer layer, a lower confinement layer, a lower waveguide layer, an active region, an upper waveguide layer, an upper confinement layer, a cap layer, a top electrode grown in sequence on the surface of a substrate, and a bottom electrode formed on the back surface of the substrate. The upper confinement layer, the cap layer, and the top electrode form a ridge. A mode regulation array structure is provided on the ridge. The mode regulation array structure includes channels and an arrow structure array. The channels are formed on both sides of the ridge. The arrow structure array includes a plurality of arrow structure units. Each arrow structure unit includes at least one arrow. Among them, the arrow structure units in the arrow structure array are formed at the peak positions of the N-1 order mode of the lateral light field distribution of the semiconductor laser, where N is an integer greater than or equal to 2. The channels can effectively suppress lateral carrier accumulation, and the arrow array structure can gradient suppress high-order modes, thereby achieving the technical effects of suppressing high-order modes, increasing the advantage of low-order modes in mode competition, making the energy distribution more concentrated, and having a lower divergence angle. In addition, this mode regulation array structure is beneficial for heat dissipation, can improve the thermal saturation phenomenon, and realize the maintenance or further increase of the output power of the semiconductor laser. At the same time, the preparation process is simple and can be compatible with large-scale preparation.

[0035] According to an embodiment of the present disclosure, in each of the arrow structure arrays, the number of arrows in the arrow structure unit increases from the center of the ridge to both sides. This is because the fundamental mode energy is mainly concentrated in the middle position of the ridge, and the number of arrows in the arrow structure unit is small, so the optical loss of the fundamental mode is small; the closer to the edge of the ridge, the number of arrows in the arrow structure unit becomes larger. Since the edge is mainly the energy of the high-order mode, the higher the mode order, the higher the loss. Thus, the technical effect of further increasing the loss of the high-order mode, increasing the advantage of the low-order mode in mode competition, and making the energy distribution more concentrated is achieved.

[0036] According to an embodiment of the present disclosure, the direction of the arrows in the arrow structure unit is consistent with the change in the peak position of the N-1 order mode when the injection current increases. Since the peak position of the high-order mode will shift as the current increases, to compensate for the thermal lens effect, the arrow direction corresponds to the change in the peak position of the high-order mode under high current injection, thereby ensuring a large loss of the high-order mode and achieving the technical effects of compensating for the thermal lens effect and improving the deterioration of the lateral divergence angle under high current injection.

[0037] Figure 1 A schematic diagram of a semiconductor laser according to an embodiment of the present disclosure is schematically shown.

[0038] As Figure 1 shown, the semiconductor laser according to an embodiment of the present disclosure includes, from bottom to top: an N-side electrode (10), an N-type substrate (1), a buffer layer (2), an N-type confinement layer (3), a lower waveguide layer (4), an active region (5), an upper waveguide layer (6), a P-type confinement layer (7), a cap layer (8), and a P-side electrode (9). A mode regulation array structure is engraved on the ridge of the semiconductor laser. The mode regulation array structure includes two long channels (12) at both edges of the ridge and 4 arrow structure arrays (13). Each arrow structure array includes 5 arrow structure units, and the arrow structure units in each arrow structure array are formed at the peak positions of the high-order modes of the lateral optical field distribution. The number of arrows in the arrow structure unit increases from the center of the ridge to both sides, and the number of arrows in the 5 arrow structure units is 1, 2, 3, 4, 5 in sequence from the center of the ridge to both sides. Since the fundamental mode energy is mainly concentrated in the middle position of the ridge, the closer to the edge of the ridge, the higher the mode order and the higher the loss. In addition, since the peak position of the high-order mode will shift as the current increases, to compensate for the thermal lens effect, the arrow direction corresponds to the change in the peak position of the high-order mode under high current injection.

[0039] According to an embodiment of the present disclosure, the width of the arrow tail of the arrow is 1-10 μm, and the width of the arrow head is 1-5 μm. Optionally, the width of the arrow tail is 4 μm, and the width of the arrow head is 2 μm.

[0040] According to an embodiment of the present disclosure, the arrow structure array is formed on both sides of the ridge near the front cavity surface and the rear cavity surface of the semiconductor laser, or formed in the middle of the ridge, or formed on one side near the front cavity surface of the semiconductor laser, or formed on the upper surface of the entire ridge. As long as an arrow structure array is provided on the surface of the ridge, the technical effects of the present disclosure can be achieved, and the embodiments of the present disclosure do not limit the position of the specific arrow structure array.

[0041] According to an embodiment of the present disclosure, the etching depth of the ridge is between the upper surface of the upper confinement layer and the lower surface of the upper waveguide layer.

[0042] According to an embodiment of the present disclosure, the etching depth of the ridge is 1 - 3 μm. Optionally, the etching depth of the ridge is 2 μm.

[0043] According to an embodiment of the present disclosure, the etching depth of the mode control structure is between the upper surface and the lower surface of the upper confinement layer to avoid excessive optical loss affecting the output power.

[0044] According to an embodiment of the present disclosure, the etching depth of the mode control structure is 1 - 3 μm. Optionally, the etching depth of the mode control structure is 2 μm.

[0045] According to an embodiment of the present disclosure, the ratio of the etched part to the unetched part of the mode control structure is 2:8 - 8:2 to minimize the gain loss of the fundamental mode as much as possible. When the etching ratio is too high, the loss of the fundamental mode will increase; when the etching ratio is too low, the loss of the high-order mode will be small. In order to balance the loss of the fundamental mode and the high-order mode, achieve the suppression of the high-order mode, increase the advantage of the low-order mode in mode competition, make the energy distribution more concentrated, and achieve the technical effect of a lower divergence angle, the ratio of the etched part to the unetched part is selected to be 2:8 - 8:2.

[0046] According to an embodiment of the present disclosure, the ratio of the etched part to the unetched part of the mode control structure is 6:4.

[0047] According to an embodiment of the present disclosure, the active region includes K1 quantum wells and K2 barrier layers, where K1 is an integer greater than or equal to 1 and K2 is an integer greater than or equal to 0. The specific number of quantum wells and barrier layers can be selected according to the actual situation, and the embodiments of the present disclosure do not limit this.

[0048] According to an embodiment of the present disclosure, the material used for the substrate is a III-V compound.

[0049] According to an embodiment of the present disclosure, the material used for the substrate is GaSb.

[0050] According to an embodiment of the present disclosure, the width of the channel is 1-5 μm. Optionally, the width of the channel is 3 μm.

[0051] Hereinafter, the semiconductor laser according to the embodiments of the present disclosure will be described in detail in conjunction with embodiments and related experiments.

[0052] Embodiment 1

[0053] The semiconductor laser structure provided by the embodiment of the present disclosure includes, from bottom to top: an N-side electrode AuGeNi, an N-type substrate GaSb; a buffer layer material of 360 nm GaTe-doped GaSb deposited on the N-type substrate in sequence, an N-type confinement layer material of 2 μm GaTe-doped Al 0.5 Ga 0.5 As 0.04 Sb 0.96 , upper and lower waveguide materials of 270 nm undoped Al 0.25 Ga 0.75 As 0.02 Sb 0.98 , an active region of two 10 nm In 0.18 Ga 0.82 Sb quantum wells and 20 nm Al 0.25 Ga 0.75 As 0.02 Sb 0.98 barrier layers, a P-type confinement layer material of 2 μm Be-doped Al 0.5 Ga 0.5 As 0.04 Sb 0.96 , a cap layer of 250 nm Be heavily doped GaSb to prevent oxidation of the epitaxial chip surface and achieve ohmic contact with the electrode, and a P-side electrode Ti / Pt / Au.

[0054] Figure 2 Schematically shows a top view of the semiconductor laser of Embodiment 1 of the present disclosure.

[0055] As Figure 2 described, the ridge width of the semiconductor laser is 100 μm, the distance from the center of the long edge channel is 90 μm, the width is 3 μm, the arrow array structure is symmetrically distributed on both sides near the front and rear cavity surfaces. Considering the first to eighth order side mode peaks, the position of the arrow tip is set to be 5-30 μm from the ridge edge, increasing by 5 μm, the width of the arrow tail is 4 μm, the width of the arrow head is 2 μm, the spacing between adjacent arrows in the cavity length direction is 20 μm, and the etching depth of the ridge and the mode control structure is 2 μm, and the etching ratio is 6:4 (the ratio of the etched part to the unetched part).

[0056] Figure 3 Schematically shows a lateral far-field pattern of the semiconductor laser of Embodiment 1 of the present disclosure.

[0057] As Figure 3 shown, the lateral far-field divergence angle of the semiconductor laser of the embodiment of the present disclosure is measured, and the full width at half maximum (FWHM) is 8.93°.

[0058] As can be seen from the above embodiments, the semiconductor laser of the embodiment of the present disclosure retains the high-power output of the wide-area laser. The etched structure array of the ridge can effectively gradient-regulate the lateral mode, suppress the high-order mode, increase the advantage of the low-order mode in mode competition, make the energy distribution more concentrated, compensate for the thermal lens effect, and suppress the accumulation of lateral carriers, improving the lateral divergence angle while maintaining the high-power output and enhancing the lateral beam quality. In addition, the preparation process of this solution is simple and compatible with large-scale preparation.

[0059] Those skilled in the art can understand that the features recited in the various embodiments and / or claims of the present disclosure can be combined and / or combined in various ways, even if such combinations or combinations are not explicitly recited in the present disclosure. In particular, without departing from the spirit and teachings of the present disclosure, the features recited in the various embodiments and / or claims of the present disclosure can be combined and / or combined in various ways. All such combinations and / or combinations fall within the scope of the present disclosure.

[0060] The above describes the embodiments of the present disclosure. However, these embodiments are for illustrative purposes only and not for limiting the scope of the present disclosure. Although the embodiments are described separately above, this does not mean that the measures in each embodiment cannot be used advantageously in combination. The scope of the present disclosure is defined by the appended claims and their equivalents. Without departing from the scope of the present disclosure, those skilled in the art can make various substitutions and modifications, and all such substitutions and modifications should fall within the scope of the present disclosure.

Claims

1. A semiconductor laser, comprising a buffer layer, a lower confinement layer, a lower waveguide layer, an active region, an upper waveguide layer, an upper confinement layer, a cap layer, a top electrode that are sequentially grown on a substrate surface, and a bottom electrode formed on the back surface of the substrate, wherein the upper confinement layer, the cap layer and the top electrode form a ridge, Characterized in that: A mode regulation array structure is arranged on the ridge, and the mode regulation array structure includes channels and an arrow structure array. The channels are formed on both sides of the ridge, and the arrow structure array includes a plurality of arrow structure units. Each arrow structure unit includes at least one arrow. Among them, the arrow structure units in the arrow structure array are formed at the peak positions of the N-1 order mode of the lateral light field distribution of the semiconductor laser, and N is an integer greater than or equal to 2; The direction of the arrow in the arrow structure unit is consistent with the change of the peak position of the N-1 order mode when the injection current increases.

2. The semiconductor laser according to claim 1, Characterized in that, In each arrow structure array, the number of arrows in the arrow structure unit increases from the center of the ridge to both sides.

3. The semiconductor laser according to claim 1, Characterized in that, The width of the arrow tail of the arrow is 1-10 μm, and the width of the arrow head is 1-5 μm.

4. The semiconductor laser according to claim 1, Characterized in that, The arrow structure array is formed on both sides of the ridge close to the front cavity surface and the rear cavity surface of the semiconductor laser, or formed in the middle of the ridge, or formed on one side close to the front cavity surface of the semiconductor laser, or formed on the upper surface of the entire ridge.

5. The semiconductor laser according to claim 1, Characterized in that, The etching depth of the ridge is between the upper surface of the upper confinement layer and the lower surface of the upper waveguide layer.

6. The semiconductor laser according to claim 4, Characterized in that, The etching depth of the ridge is 1-3 μm.

7. The semiconductor laser according to claim 1, Characterized in that, The etching depth of the mode regulation array structure is between the upper surface and the lower surface of the upper confinement layer.

8. The semiconductor laser according to claim 7, Characterized in that, The etching depth of the mode regulation array structure is 1-3 μm.

9. The semiconductor laser according to claim 7 or 8, Characterized in that, The ratio of the etched part to the unetched part of the mode regulation array structure is 2:8-8:

2.

10. The semiconductor laser according to claim 9, Characterized in that, The ratio of the etched part to the unetched part of the mode regulation array structure is 6:

4.

11. The semiconductor laser according to claim 1, Characterized in that, The active region includes K1 quantum wells and K2 barrier layers, wherein K1 is an integer greater than or equal to 1, and K2 is an integer greater than or equal to 0.

12. The semiconductor laser according to claim 1, Characterized in that, The material of the substrate is a III-V compound.

13. The semiconductor laser according to claim 12, Characterized in that, The material used for the substrate is GaSb.

14. The semiconductor laser according to claim 1, characterized in that the width of the channel is 1-5 μm.

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