A high power semiconductor optical amplifier chip

Abstract

The application belongs to the technical field of high-power semiconductor optical amplifier, and particularly relates to a high-power semiconductor optical amplifier chip, which comprises an input coupling section, a mode filtering section and a tapered main amplification section arranged in sequence from an input end to an output end along an optical propagation direction; the input coupling section, the mode filtering section and the tapered main amplification section are integrated on a same HiBBEE epitaxial structure; the HiBBEE epitaxial structure is a vertical waveguide base of the semiconductor optical amplifier chip, a non-periodic multilayer waveguide structure is introduced on an n-type cladding layer of the HiBBEE epitaxial structure; the input coupling section adopts a narrow-ridge waveguide structure; the mode filtering section adopts a narrow-ridge waveguide structure matched with the input coupling section, and a lateral corrugated structure is arranged on both sides of the ridge waveguide; the tapered main amplification section adopts a tapered ridge waveguide structure gradually widened from a narrow end to a wide end. The scheme can realize that a fundamental mode keeps a net gain advantage in the whole propagation path, high-order modes are continuously suppressed, and single transverse mode characteristics and a near-circular light beam are kept under a large-aperture output condition.

Description

Technical Field

[0001] This invention belongs to the field of high-power semiconductor optical amplifier technology, and particularly relates to a high-power semiconductor optical amplifier chip. Background Technology

[0002] High-power semiconductor optical amplifiers (SOAs) are key components in all-optical networks, with advantages such as small size, low cost, and easy integration. They are widely used in optical communication, optical sensing, lidar (LiDAR), and fiber laser pump sources. As the requirements for output power and beam quality in these applications continue to increase, high-power, high-brightness, single-mode output semiconductor optical amplifiers have become a key research direction.

[0003] For the pump source brightness limitation problem faced by high-power fiber lasers and solid-state lasers, a potential solution is to use a high-brightness, single-mode output semiconductor optical amplifier (SOA) as the pump source or preamplifier. This method couples seed light into a high-power SOA for stimulated amplification, and the high-power output light needs to maintain near-diffraction-limited beam quality to achieve efficient fiber coupling or long-distance transmission. However, the power saturation characteristics exhibited by SOAs in high-power operation are attributed to their gain saturation effect and mode competition. Therefore, to obtain high-brightness, single-mode amplification, SOAs require continuous optimization in terms of mode control, gain distribution, and beam quality, and the requirements for the amplifier's beam quality factor, saturated output power, and brightness are extremely stringent.

[0004] Currently, the commonly used high-power SOA solutions mainly include the following two types: 1. Using a traditional wide-area semiconductor optical amplifier as the amplification core, the gain area is increased by increasing the width of the ridge waveguide to achieve high power output. However, since the wide-area waveguide supports multiple lateral modes, higher-order modes compete with the fundamental mode for gain during amplification, resulting in poor output beam quality and limited brightness. Furthermore, filamentation is prone to occur at high power, which seriously affects device reliability and beam quality.

[0005] 2. Using a tapered semiconductor optical amplifier as the amplification core, employing a narrow ridge waveguide for mode filtering, and combining it with a tapered broadening section to achieve power amplification, this scheme improves beam quality to some extent. However, it still has significant drawbacks: a large vertical divergence angle, high beam ellipticity, and significant astigmatism that varies with current, requiring a complex optical system for compensation, increasing system complexity and packaging costs.

[0006] Both of the aforementioned common schemes perform mode control in a single dimension or single segment, failing to achieve continuous differentiated control of the fundamental and higher-order modes during amplification. In particular, the scheme based on a tapered structure, while achieving mode filtering through a narrow ridge, lacks a continuous suppression mechanism for higher-order modes during amplification. As propagation distance increases and thermal effects accumulate, higher-order modes gradually gain net gain, leading to beam quality degradation and an inability to maintain single-mode characteristics at large aperture outputs. Furthermore, existing schemes suffer from design deficiencies in input coupling and mode pre-filtering, resulting in low coupling efficiency and incomplete suppression of higher-order modes, further limiting the overall performance of the device.

[0007] In summary, existing high-power SOA structures mostly employ single-dimensional mode control or power amplification. Existing methods suffer from poor beam quality and filamentation in wide-area structures, while conical structures exhibit significant astigmatism that varies with current. These solutions struggle to achieve sustained single-mode amplification at high power, are limited in brightness, and have high system complexity, failing to meet the urgent demands of modern optical communication, lidar, and other fields for high brightness, high beam quality, and high-power single-mode amplification.

[0008] Therefore, there is an urgent need to design a high-power semiconductor optical amplifier chip structure that can continuously suppress higher-order modes and maintain the preferential growth of the fundamental mode during amplification, while possessing a low vertical divergence angle and near-circular beam output. Summary of the Invention

[0009] In view of this, the present invention aims to provide a high-power semiconductor optical amplifier chip to solve the technical problems of existing high-power SOA in that it is difficult to continuously suppress higher-order modes throughout the amplification path and cannot simultaneously achieve high power output and near-diffraction-limited beam quality.

[0010] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A high-power semiconductor optical amplifier chip includes an input coupling section, a mode filtering section, and a tapered main amplification section arranged sequentially from the input end to the output end along the light propagation direction; the input coupling section, the mode filtering section, and the tapered main amplification section are integrated on the same HiBBEE epitaxial structure; The HiBBEE epitaxial structure serves as the vertical waveguide basis for semiconductor optical amplifier chips. An aperiodic multilayer waveguide structure is introduced on the n-type cladding of the HiBBEE epitaxial structure. The input coupling section adopts a narrow ridge waveguide structure. The mode filtering section adopts a narrow ridge waveguide structure that matches the input coupling section, and lateral corrugated structures are set on both sides of the ridge waveguide. The tapered main amplification section adopts a tapered ridge waveguide structure that gradually widens from the narrow end to the wide end.

[0011] Furthermore, the lateral corrugated structure includes multiple geometric microstructures periodically distributed along both sides of the ridge waveguide; mode-selective scattering loss is introduced through the lateral corrugated structure.

[0012] Furthermore, the lateral corrugated structure is configured such that the fundamental mode loss propagating along the center of the ridge waveguide is less than the loss of the higher-order modes propagating along the edge of the ridge waveguide.

[0013] Furthermore, the ridge width of the narrow ridge waveguide structure in the input coupling section matches the mode field of the standard single-mode light source; the input coupling section serves as the input end for coupling with external seed light and for fundamental mode shaping.

[0014] Furthermore, the cone angle of the cone-shaped main magnification section is smaller than the diffraction angle of the fundamental mode.

[0015] Furthermore, antireflection coatings are deposited on the input end face of the input coupling section and the output end face of the tapered main amplification section.

[0016] Furthermore, the input coupling section, mode filtering section, and tapered main amplification section are integrated onto the same HiBBEE epitaxial structure using a single-wafer etching process.

[0017] Furthermore, the HiBBEE epitaxial structure includes an upper cladding layer, a quantum well active region, an n-type cladding layer, a substrate layer, and an N-side contact layer arranged sequentially along the vertical direction; the input coupling section, the mode filtering section, and the tapered main amplification section are integrated on the upper cladding layer; the upper cladding layer also includes a P-side contact layer located outside the input coupling section, the mode filtering section, and the tapered main amplification section.

[0018] Compared with the prior art, the present invention can achieve the following beneficial effects: 1. This invention employs a partitioned lateral mode control strategy to ensure that the fundamental mode maintains the highest net gain throughout the entire propagation path, while higher-order modes continuously suffer additional losses. The mode-selective scattering loss introduced by the lateral corrugated structure ensures that the loss difference between the fundamental and higher-order modes persists along the propagation direction, rather than being filtered only briefly in the input segment. This fundamentally solves the problem of mode degradation at high power. Furthermore, unlike existing technologies that filter modes only in the narrow ridge segment, this invention suppresses higher-order modes in the tapered main amplification segment through a corrugated structure. The lateral corrugated structure extends to the tapered main amplification segment, ensuring that the wide-area output still maintains single-mode characteristics. This solves the technical problem of beam quality degradation caused by the gradual oscillation of higher-order modes in the amplification segment of traditional tapered SOA.

[0019] 2. The HiBBEE epitaxial structure in this invention introduces an aperiodic multilayer structure on the n-type cladding, forming an equivalent photonic crystal waveguide effect. This causes the near-field peak of the fundamental mode to be located at the center of the active region, while higher-order vertical modes are shifted towards the substrate and generate leakage losses. This achieves single-mode emission and near-field extension in the vertical direction. This structure ensures low divergence of the single-mode in the vertical direction, and the far-field distribution in the vertical direction exhibits a single-peak distribution and a small divergence angle. Combined with lateral single-mode output, it can achieve near-circular high-brightness beam output. Through the vertical optical field extension of the HiBBEE structure and the lateral mode constraint of the lateral corrugated structure, the near-field spot is made more symmetrical, the astigmatism value is significantly reduced and the stability is improved, reducing the requirements for the subsequent collimating optical system.

[0020] 3. The narrow ridge design in this invention matches the output mode field of a standard single-mode fiber or semiconductor laser, which can effectively reduce the coupling loss between the laser and the external seed light or the pre-amplifier, increase the injection power, and ensure that the subsequent amplification process obtains sufficient input signal strength. At the same time, the SOA brightness of this solution continues to increase with the current, and can still maintain high brightness output under high power.

[0021] 4. In this invention, the tapered main amplification section adopts a tapered and widened ridge waveguide structure, which gradually widens from the narrow end to the wide end, providing stimulated amplification with a large mode field area. This enables high saturation output power and low end-face power density. At the same time, through the suppression of higher-order modes at the front end and the continuous effect of the lateral corrugation structure of the tapered main amplification section, it is possible to ensure that the single-mode characteristics are maintained under the conditions of large aperture and high power output, thus solving the contradiction between large aperture and single mode.

[0022] 5. In this invention, the input coupling section, mode filtering section, and tapered main amplification section are based on the same HiBBEE epitaxial structure and are monolithically integrated through a single-wafer etching process. It adopts standard semiconductor laser technology, is compatible with existing production lines, does not require multiple epitaxy or complex selective region growth, has controllable manufacturing costs, and has good process compatibility. Attached Figure Description

[0023] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 This is a schematic diagram of the overall structure of the semiconductor optical amplifier chip in an embodiment of the present invention; Figure 2 This is a top view of the semiconductor optical amplifier chip in an embodiment of the present invention; Figure 3 This is a top view of a reference semiconductor optical amplifier chip used for reference in an embodiment of the present invention; Figure 4This is a schematic diagram of the fundamental mode and higher-order mode losses of the semiconductor optical amplifier chip and the reference semiconductor optical amplifier chip in an embodiment of the present invention; Figure 5 This is a schematic diagram of the mode loss difference between the semiconductor optical amplifier chip and the reference semiconductor optical amplifier chip in an embodiment of the present invention. Figure 6 This is a schematic diagram of the longitudinal divergence angle of the semiconductor optical amplifier chip in an embodiment of the present invention; Figure 7 This is a schematic diagram of the longitudinal divergence angle of the reference semiconductor optical amplifier chip in an embodiment of the present invention; Figure 8 This is a schematic diagram of the lateral divergence angle of the semiconductor optical amplifier chip in an embodiment of the present invention; Figure 9 This is a schematic diagram of the lateral divergence angle of the reference semiconductor optical amplifier chip in an embodiment of the present invention; Figure 10 This is a lateral mode distribution diagram of the semiconductor optical amplifier chip in an embodiment of the present invention; Figure 11 This is a schematic diagram comparing the brightness of the semiconductor optical amplifier chip and a reference semiconductor optical amplifier chip in an embodiment of the present invention.

[0024] Figure reference numerals: 1. N-side contact layer, 2. Substrate layer, 3. n-type cladding, 4. Quantum well active region, 5. Upper cladding, 6. P-side contact layer, 7. Input coupling section, 8. Mode filtering section, 9. Tapered main amplification section, 10. Electrode structure, 11. Lateral corrugated structure. Detailed Implementation

[0025] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0026] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0027] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0028] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0029] The following will refer to the appendix. Figure 1-11 The invention will be described in detail with reference to the embodiments.

[0030] A high-power semiconductor optical amplifier chip includes three functional segments arranged sequentially from the input end to the output end along the light propagation direction: an input coupling segment 7, a mode filtering segment 8, and a tapered main amplification segment 9. The input coupling segment 7, the mode filtering segment 8, and the tapered main amplification segment 9 are integrated on the same HiBBEE epitaxial structure through a monolithic etching process. In this embodiment, the mode field of each functional segment is matched with the propagation mode, which can improve amplification efficiency and beam quality.

[0031] The HiBBEE epitaxial structure serves as the vertical waveguide basis for semiconductor optical amplifier chips, providing an active part with low noise, high gain, and low vertical divergence angle. An aperiodic multilayer waveguide structure is introduced on the n-type cladding 3 of the HiBBEE epitaxial structure, which is composed of multiple layers of materials with different refractive indices. The semiconductor optical amplifier is the SOA (Semiconductor Optical Amplifier).

[0032] The HiBBEE epitaxial structure includes an upper cladding layer 5, a quantum well active region 4, an n-type cladding layer 3, a substrate layer 2, and an N-side contact layer 1 arranged sequentially along the vertical direction; an input coupling section 7, a mode filtering section 8, and a tapered main amplification section 9 are integrated on the upper cladding layer 5; the upper cladding layer 5 also includes a P-side contact layer 6 located outside the input coupling section 7, the mode filtering section 8, and the tapered main amplification section 9.

[0033] The N-side contact layer 1 is used to achieve ohmic contact with the external power supply, inject electron carriers into the device, provide current drive for the active region, and realize the stimulated emission amplification process; the substrate layer 2 provides mechanical support and epitaxial growth basis for the device, usually an n-doped semiconductor material, and also serves as a thermal conduction path to facilitate heat dissipation; the n-type cladding layer 3 serves as a carrier for the non-periodic multilayer waveguide structure, and works together to achieve a low vertical divergence angle, which can extend the near-field distribution in the vertical direction and reduce the divergence angle, providing single-mode amplification in the vertical direction.

[0034] The active region 4 of the quantum well is the core region for stimulated emission amplification. Under the injection of an external current, charge carriers recombine in this region and generate an optical amplification effect. This region highly overlaps with the optical field distribution, and its confinement factor directly affects the gain characteristics and efficiency of the device. The upper cladding layer 5 is used to form a refractive index difference to achieve vertical confinement of the optical field, while providing a current injection path and reducing the outward leakage of the optical field. The P-side contact layer 6 is used to achieve hole injection, which together with the N-side contact layer 1 forms a current injection path, enabling charge carrier recombination in the active region, thereby achieving optical amplification.

[0035] The input coupling section 7 adopts a narrow ridge waveguide structure and is located on the input end face of the chip. The ridge width of the narrow ridge waveguide structure matches the mode field of the standard single-mode light source, which can adjust the coupling efficiency and achieve low-loss fundamental mode injection. The input coupling section 7 serves as the input end for coupling with external seed light or pre-amplifier. The main function of the input coupling section 7 is to receive and stabilize the fundamental mode light field, complete the fundamental mode shaping, and provide a clean fundamental mode input for the subsequent mode filtering section 8 and tapered main amplification section 9. The input end face of the input coupling section 7 is coated with an anti-reflection film to reduce the Fabry-Perot effect and return loss caused by end face reflection.

[0036] The mode filtering section 8 is located after the input coupling section 7. It adopts a narrow ridge waveguide structure that matches the input coupling section 7 to pre-suppress higher-order modes entering the amplification section. Lateral corrugated structures 11 are set on both sides of the ridge waveguide to achieve partitioned mode control. The lateral corrugated structures 11 are configured such that the loss of the fundamental mode propagating along the center of the ridge waveguide is less than the loss of the higher-order modes propagating along the edge of the ridge waveguide. The lateral corrugated structures 11 include multiple geometric microstructures that are periodically distributed along both sides of the ridge waveguide. Mode-selective scattering loss is introduced through the lateral corrugated structures 11. Differentiated loss between the fundamental mode and higher-order modes is achieved by modulating the scattering loss. The device is simple to fabricate and has a low cost.

[0037] The main function of mode filtering section 8 is to suppress higher-order transverse modes such as TE1 and TM1 before the light field enters the wide-area amplification. By introducing selective scattering loss through the lateral corrugated structure 11, the loss difference between the fundamental mode and higher-order modes is increased, ensuring that the light field entering the conical main amplification section 9 is a pure fundamental mode.

[0038] The tapered main amplification section 9 is located after the mode filtering section 8. It adopts a tapered ridge waveguide structure that gradually widens from the narrow end to the wide end. The tapered angle of the tapered main amplification section 9 is smaller than the diffraction angle of the fundamental mode. The main function of the tapered main amplification section 9 is to provide stimulated amplification with a large mode field area, so as to achieve high saturation output power and low end-face power density. At the same time, by suppressing higher-order modes at the front end, it ensures that the single transverse mode characteristics are maintained under large-aperture high-power output conditions. The output end face of the tapered main amplification section 9 is coated with an anti-reflection film to reduce feedback and improve output efficiency.

[0039] The semiconductor optical amplifier chip also includes an electrode structure 10, which is used to inject current into each functional segment.

[0040] Working principle: This embodiment is based on a partitioned lateral mode control strategy. By continuously adjusting the net gain difference between the fundamental mode and higher-order modes during the amplification process, it achieves the selective net gain advantage of the fundamental mode and the continuous suppression of higher-order modes.

[0041] Fundamental mode selective net gain: In the stimulated amplification process of semiconductor optical amplifier, the net gain of each mode is determined by the mode gain, confinement factor, internal loss and scattering loss. In this embodiment, mode selective scattering loss is introduced by the lateral corrugated structure 11. Specifically, the fundamental mode optical field is concentrated in the central region of the ridge waveguide, and its interaction with the lateral corrugated structure 11 is weak, resulting in small scattering loss. The higher-order mode optical field extends to the edge region of the ridge waveguide and interacts strongly with the lateral corrugated structure 11, resulting in significant scattering loss. By optimizing the geometric parameters and distribution of the corrugated structure, the fundamental mode satisfies the condition that the net gain is positive, and the higher-order modes satisfy the condition that the net gain is negative or much lower than that of the fundamental mode, thereby achieving continuous amplification of the fundamental mode and continuous suppression of the higher-order modes during propagation.

[0042] Partitioned mode control: In this embodiment, three functional segments are set along the light propagation direction. Each segment is optimized for different mode control objectives. The input coupling segment 7 adopts a straight ridge structure to avoid introducing additional losses and ensure low-loss coupling and stable input of the fundamental mode. The mode filtering segment 8 adopts a corrugated structure of medium depth to pre-introduce additional losses of higher-order modes before the light field enters the wide area and pre-filters out higher-order modes to achieve full single-mode retention from input to output.

[0043] Vertical single-mode extension: The HiBBEE epitaxial structure used in this embodiment introduces an aperiodic multilayer structure on the n-type cladding 3 to form an equivalent photonic crystal waveguide effect. This structure makes the near-field peak of the fundamental mode located at the center of the active region, while the higher-order vertical modes are shifted towards the substrate and generate higher leakage loss. The confinement factor of the fundamental mode is greater than that of the higher-order modes, while the leakage loss is much smaller than that of the higher-order modes, thereby realizing single-mode emission and near-field extension in the vertical direction, reducing the vertical divergence angle, and realizing near-circular beam output.

[0044] In high-power semiconductor lasers or optical amplifiers, brightness is an important indicator of the overall performance of beam quality and output power. It is defined as the optical power density per unit phase space. The brightness of a semiconductor laser is expressed as: ; in, For output power, λ For the emission wavelength, This is the transverse beam quality factor. Let be the longitudinal beam quality factor. This equation shows that increasing output power... The introduction of the lateral corrugated structure 11 can significantly improve the brightness by reducing the beam quality factor. Due to the increased loss of higher-order modes and the dominance of the fundamental mode, the transverse beam quality is significantly improved, thereby improving the overall brightness and realizing high-brightness, high-power single-mode beam amplification.

[0045] Figure 1 The overall structure of the semiconductor optical amplifier chip in this embodiment is shown; Figure 2 The top view of the semiconductor optical amplifier chip in this embodiment is shown; Figure 3 The diagram shows a top view of a reference semiconductor optical amplifier chip used as a reference in an embodiment of the present invention. Figure 3 The middle S section represents the existing undivided single cone structure.

[0046] Figure 2 In the process, the input coupling section 7 can maximize the coupling efficiency between the external seed light and the chip, thereby increasing the final injection power. The input coupling section 7 is a narrow ridge waveguide structure, and its ridge width matches that of a standard single-mode light source, which facilitates the reception of the fundamental mode and reduces coupling loss. The waveguide can be a straight waveguide or a curved waveguide with a certain angle. Alternatively, the mode field can be further matched through etching depth design to further suppress the excitation of higher-order modes.

[0047] Depend on Figure 2It can be seen that the mode filtering section 8 mainly includes a medium-depth lateral corrugated structure 11, which aims to pre-suppress higher-order lateral modes before entering the conical main amplification section 9. The corrugation size and period are optimized to introduce additional scattering loss of higher-order modes while maintaining low loss of the fundamental mode. The loss difference between the fundamental mode and higher-order modes can be continuously adjusted in the propagation direction. When the net gain of the higher-order mode is lower than that of the fundamental mode, the semiconductor optical amplifier amplifies in single mode. The optimization of the lateral corrugated structure 11 can also realize single-mode operation under different currents.

[0048] Figure 2 In the main amplification section 9, a tapered, broadened ridge waveguide structure is designed to achieve single-mode power amplification with a large aperture. The tapered angle is smaller than the fundamental mode diffraction angle to prevent higher-order mode coupling. The corrugated structure maintains scattering suppression of higher-order modes over a wide region, thereby achieving high-power single-mode output. Electrode structure 10 is used to inject current into the semiconductor optical amplifier chip. Its rear end has leads connected to an external driving power supply. After finding the optimal injection position, each electrode is fixed on the chip to improve the injection efficiency of the entire semiconductor optical amplifier.

[0049] Figure 4 The diagram illustrates the fundamental and higher-order mode losses of the semiconductor optical amplifier chip and the reference semiconductor optical amplifier chip in this embodiment. Line 1 represents the fundamental and higher-order mode losses of the reference semiconductor optical amplifier chip, while line 2 represents the fundamental and higher-order mode losses of the semiconductor optical amplifier chip in this embodiment. This indicates the difference in propagation loss of different lateral modes in the waveguide. The fundamental mode is mainly concentrated in the central region of the ridge waveguide, resulting in lower loss, while the higher-order modes are distributed closer to the sidewalls and interact more strongly with the lateral corrugated structure 11, thus generating greater scattering loss.

[0050] Figure 5 The diagram shows the mode loss difference between the semiconductor optical amplifier chip and the reference semiconductor optical amplifier chip in this embodiment. It indicates that after introducing the lateral ripple structure 11, the loss difference of higher-order modes increases significantly, demonstrating that the structure in this solution can effectively improve the loss difference between the fundamental mode and higher-order modes, thereby enhancing the mode selection capability and achieving higher-order mode suppression. Figure 6 This is a schematic diagram of the longitudinal divergence angle of the semiconductor optical amplifier chip in an embodiment of the present invention. It shows the far-field distribution of the semiconductor optical amplifier based on the HiBBEE epitaxial structure in the vertical direction. The light field is extended in the vertical direction, exhibiting a single-peak distribution and a small divergence angle.

[0051] Figure 7 This is a schematic diagram of the longitudinal divergence angle of the reference semiconductor optical amplifier chip in this embodiment. It shows the far-field distribution of the traditional semiconductor optical amplifier in the vertical direction. Its divergence angle is large and the beam quality is poor, indicating that the present solution has better beam quality in the vertical direction.

[0052] Figure 8 This diagram illustrates the lateral divergence angle of the semiconductor optical amplifier chip in this embodiment under different injection currents. It shows that after lateral mode modulation, the lateral far-field distribution exhibits a single-peak characteristic, higher-order modes are suppressed, and the divergence angle decreases. In the diagram, I1, I2, I3, and I4 represent the injection current, indicating that the current gradually increases.

[0053] Figure 9 This diagram illustrates the lateral divergence angle of the reference semiconductor optical amplifier chip in this embodiment under different injection currents. It shows that without the introduction of a mode modulation structure, the lateral far field exhibits a multi-peak structure, corresponding to multimode output, and a large divergence angle. This demonstrates that lateral mode modulation effectively improves the lateral beam quality. In the diagram, I1, I2, I3, and I4 represent the injection current, indicating that the current gradually increases.

[0054] Figure 10 This is a lateral mode distribution diagram of the semiconductor optical amplifier chip in this embodiment, showing the spatial distribution of different lateral modes in SOA. Line 1 is the fundamental mode, mainly concentrated in the center of the ridge waveguide and the active region, with a high confinement factor; lines 2 and 3 are higher-order modes, distributed towards the edge of the waveguide, and coupled more strongly with the lateral corrugated structure 11, resulting in lower fundamental mode loss and net gain, while higher-order mode loss is greater and gradually suppressed, reflecting the "selective mode amplification mechanism" of this scheme.

[0055] Figure 11 This diagram illustrates the brightness comparison between the semiconductor optical amplifier chip in this embodiment and a reference semiconductor optical amplifier chip, showing the brightness variation of different semiconductor optical amplifier structures under different driving currents. Line 1 represents the brightness of the reference semiconductor optical amplifier chip, and line 2 represents the brightness of the semiconductor optical amplifier chip in this embodiment. The results show that the brightness of the semiconductor optical amplifier in this solution continuously increases with current, and it has a greater advantage in brightness than the reference semiconductor optical amplifier under high current. This solution can still maintain high brightness output under high power.

[0056] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0057] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A high-power semiconductor optical amplifier chip, characterized in that: It includes an input coupling section (7), a mode filtering section (8), and a tapered main amplification section (9) arranged sequentially from the input end to the output end along the light propagation direction; the input coupling section (7), the mode filtering section (8), and the tapered main amplification section (9) are integrated on the same HiBBEE epitaxial structure; The HiBBEE epitaxial structure is the vertical waveguide basis of the semiconductor optical amplifier chip. An aperiodic multilayer waveguide structure is introduced on the n-type cladding (3) of the HiBBEE epitaxial structure. The input coupling section (7) adopts a narrow ridge waveguide structure. The mode filtering section (8) adopts a narrow ridge waveguide structure that matches the input coupling section (7), and lateral corrugated structures (11) are set on both sides of the ridge waveguide. The tapered main amplification section (9) adopts a tapered ridge waveguide structure that gradually widens from the narrow end to the wide end. The lateral corrugated structure (11) includes multiple geometric microstructures periodically distributed along both sides of the ridge waveguide; mode-selective scattering loss is introduced through the lateral corrugated structure (11); the lateral corrugated structure (11) is configured such that the loss of the fundamental mode propagating along the center of the ridge waveguide is less than the loss of the higher-order modes propagating along the edge of the ridge waveguide; the cone angle of the cone-shaped main amplification section (9) is less than the diffraction angle of the fundamental mode.

2. The high-power semiconductor optical amplifier chip according to claim 1, characterized in that: The ridge width of the narrow ridge waveguide structure in the input coupling section (7) matches the mode field of the standard single-mode light source; the input coupling section (7) serves as the input end for coupling with external seed light and for fundamental mode shaping.

3. The high-power semiconductor optical amplifier chip according to claim 1, characterized in that: Anti-reflection coatings are applied to the input end face of the input coupling section (7) and the output end face of the tapered main amplification section (9).

4. The high-power semiconductor optical amplifier chip according to claim 1, characterized in that: The input coupling section (7), the mode filtering section (8), and the tapered main amplification section (9) are integrated on the same HiBBEE epitaxial structure through a single-wafer etching process.

5. The high-power semiconductor optical amplifier chip according to claim 1, characterized in that: The HiBBEE epitaxial structure includes an upper cladding (5), a quantum well active region (4), an n-type cladding (3), a substrate layer (2), and an N-side contact layer (1) arranged sequentially along the vertical direction; an input coupling section (7), a mode filtering section (8), and a tapered main amplification section (9) are integrated on the upper cladding (5); the upper cladding (5) also includes a P-side contact layer (6) located outside the input coupling section (7), the mode filtering section (8), and the tapered main amplification section (9).

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