Photonic crystal surface emitting laser, light source, and projection device

Abstract

The application discloses a photonic crystal surface emitting laser, a light source and a projection device, and belongs to the technical field of semiconductors. The photonic crystal surface emitting laser comprises a photonic crystal layer, and the photonic crystal layer comprises: a photonic crystal layer base material and a plurality of three-lattice units arranged in an array on the photonic crystal layer base material; the three-lattice unit comprises a first photonic crystal structure and two second photonic crystal structures, and the geometric center of the first photonic crystal structure and the geometric centers of the two second photonic crystal structures cooperatively form a triangle. The projection shape of the first photonic crystal structure on a plane parallel to the photonic crystal layer is a circle, and the projection shape of the second photonic crystal structure on the plane parallel to the photonic crystal layer is an ellipse, a triangle or a non-circular pattern with central symmetry and more than three sides. The laser is excellent in single-mode stability, beam quality, power output and wavelength regulation and the like.

Description

Technical Field

[0001] This disclosure relates to the field of semiconductor technology, and in particular to photonic crystal surface-emitting lasers, light sources, and projection devices. Background Technology

[0002] Photonic crystal surface-emitting lasers (PCSELs) are semiconductor lasers that utilize the band-edge resonance effect of photonic crystals to achieve in-plane light feedback and perpendicular surface light emission by introducing a two-dimensional photonic crystal structure. They can achieve narrow divergence angle, narrow linewidth, high power, and single-mode output, and are widely used in scenarios requiring narrow divergence angle emission beams and high output power.

[0003] A photonic crystal surface-emitting laser includes a photonic crystal layer (PC layer). The photonic crystal structure is formed by creating holes in the photonic crystal layer and filling them with materials of different refractive indices (such as air or other dielectric materials). The photonic crystal structure, as a resonant structure, determines the beam output effect of the photonic crystal surface-emitting laser.

[0004] However, current photonic crystal surface-emitting lasers typically have single-lattice or dual-lattice photonic crystal layers. Nevertheless, these single-lattice and dual-lattice photonic crystal surface-emitting lasers still need improvement in terms of single-mode stability, beam quality, power output, and wavelength control. Summary of the Invention

[0005] This disclosure provides a photonic crystal surface-emitting laser, a light source, and a projection device. It specifically provides a photonic crystal surface-emitting laser with a three-lattice structure, which exhibits superior performance in single-mode stability, beam quality, power output, and wavelength control, thus addressing the technical problems existing in related technologies. Specifically, the technical solution is as follows.

[0006] On one hand, a photonic crystal surface-emitting laser is provided, the photonic crystal surface-emitting laser including a photonic crystal layer, the photonic crystal layer including: a photonic crystal layer substrate and a plurality of three-lattice units arranged in an array on the photonic crystal layer substrate; the three-lattice units include a first photonic crystal structure and two second photonic crystal structures, the geometric centers of the first photonic crystal structure and the geometric centers of the two second photonic crystal structures forming a triangle; wherein, the projection shape of the first photonic crystal structure on a plane parallel to the photonic crystal layer is circular, and the projection shape of the second photonic crystal structure on a plane parallel to the photonic crystal layer is elliptical, triangular, or a centrally symmetric non-circular shape with more than 3 sides.

[0007] The photonic crystal surface-emitting laser provided in this disclosure employs a three-lattice photonic crystal structure. Compared to single-lattice and dual-lattice photonic crystal structures, multiple three-lattice units are arranged in a periodic array for coordinated control. On one hand, this allows for precise control of the photonic crystal's bandgap characteristics, enhancing the ability to confine optical modes and achieving superior mode control and single-mode stability. On the other hand, it facilitates the formation of multiple Bragg scattering mechanisms, improving the quality factor of the resonant cavity. Furthermore, it allows for more flexible beam control by optimizing lattice symmetry and adjusting the parameters of the three lattices, resulting in beams with low divergence angles and high directionality. Moreover, the three-lattice photonic crystal structure not only supports single-mode operation with a larger emission area but also more easily disperses thermal stress, achieving high power output and thermal management. Finally, by adjusting the lattice constant or material composition of the three-lattice photonic crystal structure, wavelength tuning can be achieved over a wider spectral range (e.g., from near-infrared to visible light).

[0008] It is evident that the three-lattice PCSEL, through multi-dimensional photonic bandgap collaborative design, outperforms traditional single / double-lattice PCSELs in terms of single-mode stability, beam quality, power output, and wavelength control.

[0009] Specifically, the three-lattice unit comprises a circular first photonic crystal structure and two identical non-circular second photonic crystal structures. The second photonic crystal structures are elliptical, triangular, or centrally symmetric non-circular shapes with more than three sides. This combination of circular and non-circular photonic crystal structures forms a three-lattice unit. Compared to a fully isomorphic three-lattice unit (e.g., three circular or three elliptical photonic crystal structures), the symmetry of the circular structure and the anisotropy of the non-circular structure, based on these advantages, firstly, enhances the anisotropic bandgap tuning capability of the laser, expands the bandgap coverage, and further improves single-mode stability. Secondly, it facilitates simultaneous control of the beam divergence angle and its directionality. Furthermore, the different shapes of the photonic crystal structures facilitate anisotropic scattering, forming asymmetric refractive index modulation, which more easily covers complex mode competition scenarios. Finally, by independently adjusting the lattice parameters of the first or second photonic crystal structure, it is easier to achieve finer wavelength tuning or multi-band integration.

[0010] As can be seen, the combined design of circular and non-circular photonic crystal structures involved in this disclosure, through the synergistic effect of symmetric and asymmetric scattering mechanisms, outperforms fully isomorphic photonic crystal structures (such as three circular or three elliptical photonic crystal structures) in terms of single-mode stability, beam control flexibility, and wavelength tuning and extension. This gives the laser provided by this disclosure significant advantages in scenarios involving directional output, multi-physics field manipulation, or complex integration.

[0011] This disclosure expands upon more types of three-lattice photonic crystal surface-emitting lasers. By adjusting parameters such as the material, shape, size, and arrangement of each photonic crystal structure in the three-lattice unit, the relevant parameters of the emitted beam (e.g., emission wavelength, divergence angle, emission direction, focusing, etc.) and emission power can be adjusted accordingly, enabling the photonic crystal surface-emitting laser to output in a specific output mode and maintain high beam quality and power density even under large-area conditions.

[0012] In some possible implementations, the triangles mentioned above can be equilateral triangles, isosceles triangles, and non-isosceles triangles are not excluded. The centrally symmetric non-circular figures with more than 3 sides mentioned above can be rectangles, squares, rhombuses, or regular polygons with more than or equal to 5 sides.

[0013] Furthermore, the second photonic crystal structure is elliptical in shape. The elliptical photonic crystal structure, based on its major and minor axes, allows for stronger localized control of the optical field. This is beneficial for enhancing the laser's photonic bandgap modulation capability, improving optical field confinement and mode control, controlling the beam divergence angle, improving beam uniformity, and increasing output power. The combination of a circular photonic crystal structure and two elliptical photonic crystal structures is more advantageous for lasers that output beams with narrow linewidths, high power, and narrow divergence angles.

[0014] In some possible implementations, along a plane parallel to the direction of the photonic crystal layer, the coordinates of the geometric center of the first photonic crystal structure are reference coordinates (x0, y0), and the coordinates of the geometric centers of the two second photonic crystal structures are (x1, y1) and (x2, y2), respectively; wherein the coordinates of the geometric centers of the first photonic crystal structure and the second photonic crystal structure satisfy: x0 is less than both x1 and x2, and y0 is equal to one of y1 and y2 and greater than the other of y1 and y2.

[0015] This configuration allows the photonic crystal surface-emitting laser to output a beam with narrow linewidth, high power, and narrow divergence angle, and even obtain a Gaussian spot with robust characteristics. Moreover, it also helps to improve the power utilization rate of the laser, which can solve the technical problem of low power utilization rate of lasers in related technologies.

[0016] In some possible implementations, the distance between the geometric center of the first photonic crystal structure and the geometric centers of the two second photonic crystal structures is defined as S1 and S2, respectively, and the distance between the geometric centers of the two second photonic crystal structures is defined as S3. S1, S2 and S3 satisfy the condition that S1 and S2 are both less than S3, so as to further promote the output of a narrow linewidth, high power and narrow divergence angle beam from the photonic crystal surface-emitting laser.

[0017] In some possible implementations, the diameter of the first photonic crystal structure is larger than the minor axis and smaller than the major axis of the second photonic crystal structure. This is beneficial for enabling the laser to achieve a wide bandgap and strong feedback, which is conducive to stable single-mode output and improves beam quality and output efficiency. For example, it can obtain a Gaussian spot with robust characteristics.

[0018] In some possible implementations, the two long axes of the two second photonic crystal structures are parallel. In this case, the three lattice units have high symmetry, which further promotes the output of a narrow linewidth, high power, and narrow divergence angle laser beam, and makes it easier to obtain a robust Gaussian spot.

[0019] In some possible implementations, the distance between the geometric centers of any two adjacent three-lattice units is defined as w. Along the plane parallel to the direction of the photonic crystal layer, the coordinates of the geometric center of the first photonic crystal structure are (0.1-0.2, 0.5-0.8)w, the coordinates of the geometric centers of the two second photonic crystal structures are (0.2-0.5, 0.1-0.2)w and (0.5-0.8, 0.5-0.8)w respectively, and the diameter of the first photonic crystal structure is 0.1w-0.2w, the major axis dimension of the second photonic crystal structure is 0.1w-0.5w, and the minor axis dimension of the second photonic crystal structure is 0.05w-0.15w.

[0020] This approach facilitates the achievement of a wide bandgap and strong feedback, enabling stable single-mode output, thereby improving beam quality and output efficiency. It allows the laser to output a beam with narrow linewidth, high power, and narrow divergence angle, thus obtaining a robust Gaussian spot with a power utilization rate of at least 80%.

[0021] In some possible implementations, the coordinates of the geometric center of the first photonic crystal structure are (0.1-0.15, 0.6-0.7)w, the coordinates of the geometric centers of the two second photonic crystal structures are (0.25-0.4, 0.12-0.18)w and (0.55-0.7, 0.55-0.7)w respectively, the diameter of the first photonic crystal structure is 0.1w-0.15w, the major axis dimension of the second photonic crystal structure is 0.1w-0.3w, and the minor axis dimension of the second photonic crystal structure is 0.05w-0.1w.

[0022] Based on the above technical solution, the photonic crystal surface-emitting laser can emit a Gaussian spot with a divergence angle of less than 1 degree * 1 degree, and the power utilization rate of the photonic crystal surface-emitting laser reaches more than 90%.

[0023] In some possible implementations, the array of multiple said three-lattice units includes a square array, a circular array, an elliptical array, a rhombus array, or a regular polygon array with a number of sides greater than or equal to 5.

[0024] Multiple three-lattice units can be arranged in a periodic array to precisely and controllably regulate the light emission performance of the photonic crystal layer, thereby optimizing the light field distribution and emission characteristics of the laser.

[0025] In some possible implementations, the photonic crystal surface-emitting laser further includes an n-type electrode, an n-type cladding, a multiple quantum well layer, an electron blocking layer, a first gradient layer, a regenerated layer, a second gradient layer, a p-type cladding, a third gradient layer, a p-type contact layer, and a p-type electrode; the n-type electrode, the n-type cladding, the multiple quantum well layer, the electron blocking layer, the first gradient layer, the photonic crystal layer, the regenerated layer, the second gradient layer, the p-type cladding, the third gradient layer, the p-type contact layer, and the p-type electrode are stacked sequentially.

[0026] The multi-layer design of the photonic crystal surface-emitting laser effectively avoids the shortcomings of EEL and VCSEL, giving it advantages such as surface emission, high output beam power, narrow linewidth, and single-mode output, and the ability to output Gaussian beams under specific conditions.

[0027] In some possible implementations, the photonic crystal layer substrate is made of indium gallium arsenide, aluminum gallium indium arsenide, gallium arsenide, or indium phosphide.

[0028] In some possible implementations, the first photonic crystal structure and the two photonic crystal structures are air holes or dielectric pillars, and the material of the dielectric pillars is selected from elements, alloys or compounds of Group III-V, II-VI or IV.

[0029] For photonic crystal structures with air holes, the air holes can be considered to be filled with air. They are suitable for applications requiring high refractive index contrast and wide bandgap. For example, the air hole can penetrate the photonic crystal layer. For photonic crystal structures with dielectric pillars, the air holes are filled with dielectric material to form dielectric pillars. They are suitable for applications requiring medium refractive index contrast and narrow bandgap. The choice depends on the specific needs.

[0030] On the other hand, a light source is provided, the light source including a printed circuit board and a laser array, the laser array being disposed on the printed circuit board, the laser array including a plurality of photonic crystal surface-emitting lasers as described above.

[0031] The light source provided in this disclosure has all the advantages of the photonic crystal surface-emitting laser described above.

[0032] In another aspect, a projection device is provided, which includes the aforementioned light source, modulator, and lens. The modulator is used to modulate the light beam emitted by the light source and output a light signal, and the lens is used to transmit the light signal to output a projected image.

[0033] The projection device provided in this disclosure has all the advantages of the photonic crystal surface-emitting laser or light source mentioned above.

[0034] The projection device provided in this disclosure can be applied to a variety of scenarios, including but not limited to: PCSEL projection device or projector, vehicle display device, security monitoring device, home theater, augmented reality and virtual reality device, medical imaging device, etc. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the structure of a first exemplary photonic crystal layer provided in an embodiment of the present disclosure;

[0036] Figure 2 This is a schematic diagram of the structure of a second exemplary photonic crystal layer provided in an embodiment of this disclosure;

[0037] Figure 3 This is a schematic diagram of the structure of a third exemplary photonic crystal layer provided in an embodiment of this disclosure;

[0038] Figure 4 This is a schematic diagram of the structure of the fourth exemplary photonic crystal layer provided in the embodiments of this disclosure;

[0039] Figure 5 This is a schematic diagram of the structure of the fifth exemplary photonic crystal layer provided in the embodiments of this disclosure;

[0040] Figure 6 A side view of an exemplary photonic crystal surface-emitting laser provided for embodiments of this disclosure;

[0041] Figure 7 A simulation output diagram of the output spot of an exemplary photonic crystal surface-emitting laser provided in this embodiment of the present disclosure;

[0042] Figure 8 This is a simulated output combination diagram of the output beams of multiple photonic crystal surface-emitting lasers provided in the embodiments of this disclosure.

[0043] in, Figure 7 The x-coordinate θ x The divergence angle is θ along the x-axis, and the ordinate on the left is θ. y The y-axis represents the divergence angle, and the ordinate on the right represents the brightness of the light spot.

[0044] Figure 8 In the figures, E_(far) refers to the far-field spot size, noise=5 indicates a process error of 5nm, meaning the perturbation error range is [-5nm, 5nm], and seed is the seed number, which is also the figure number; each figure number represents a test sample. Figure 8 The image shows a combination of simulation output graphs for 50 samples, from seed=1 to seed=50. The simulation output graph for each sample can be used as a reference. Figure 7 The coordinate values ​​in the simulation output graphs of these 50 samples may differ from... Figure 7 ,because Figure 8 Due to limited space, all coordinates will not be shown here; they are only provided for illustrative purposes.

[0045] The reference numerals in the attached figures represent:

[0046] 100. Photonic crystal layer substrate;

[0047] 200. Triple lattice unit; 201. Circular photonic crystal structure; 202. Second photonic crystal structure; 202a. Elliptical photonic crystal structure; 202b. Triangular photonic crystal structure; 202c. Rectangular photonic crystal structure; 202d. Regular polygonal photonic crystal structure;

[0048] 001, n-type electrode; 002, n-type cladding; 003, multiple quantum well layer; 004, electron blocking layer; 005, first gradient layer; 006, photonic crystal layer; 007, regeneration layer; 008, second gradient layer; 009, p-type cladding; 0010, third gradient layer; 0011, p-type contact layer; 0012, p-type electrode. Detailed Implementation

[0049] Currently, lasers have undergone the following developments: edge-emitting lasers (EELs), vertical-cavity surface-emitting lasers (VCSELs), and photonic crystal surface-emitting lasers (PCSELs). EELs have an olive-shaped output beam, making them unsuitable for precision machining. While VCSELs have a circular output beam, their output power is typically in the milliwatt (mW) range, causing it to attenuate to almost zero over short distances. For long-distance transmission, additional optical signal amplification is required for VCSELs, indirectly increasing their application cost and structural complexity. In contrast, PCSELs typically have output power in the watt (W) range, a significant improvement over VCSELs. This means their output power does not attenuate to zero even after long distances. Furthermore, as surface-emitting lasers, their emitted beam is naturally symmetrical, requiring no calibration. Furthermore, the divergence angle of the emitted beam from a PCSEL is extremely narrow, maintaining this narrow divergence angle even after propagating a considerable distance (tens or even hundreds of meters). Clearly, PCSEL overcomes the shortcomings of EELs and VCSELs, possessing advantages such as surface emission, high emitted beam power, narrow linewidth, and single-mode output. It can output a Gaussian beam, which refers to a beam formed by a cylindrical, symmetrical structure with an extremely narrow divergence angle.

[0050] For laser applications such as laser processing (metal cutting, etching, etc.) and atmospheric laser communication, it is not only required that the laser beam emitted by the source maintains its original shape and does not diverge after propagating a long distance, but also that the beam has high power to facilitate long-distance transmission and avoid attenuation to zero after a short transmission distance. Therefore, PCSELs are more adaptable to these scenarios.

[0051] PCSEL comprises multiple semiconductor layers stacked together, one of which is a photonic crystal layer. The photonic crystal layer includes a photonic crystal substrate and multiple periodically arranged lattice units disposed on the substrate. Each lattice unit comprises one or more photonic crystal structures. By incorporating periodically arranged openings of different shapes and sizes within the photonic crystal layer, these openings penetrate the entire layer. The openings can be left unfilled (i.e., air-filled) to form air-hole photonic crystal structures, or they can be filled with a semiconductor dielectric material with a specific refractive index to form dielectric pillar photonic crystal structures. Thus, the refractive index of the lattice units containing the photonic crystal structures differs from that of the photonic crystal substrate, thereby creating a photonic bandgap based on this refractive index difference, and ultimately achieving quantum control of the light field.

[0052] As a resonant structure, the photonic crystal structure has a significant impact on the output performance of PCSELs. Multiple photonic crystal structures are arranged in a periodic array within the photonic crystal layer. The smallest repeating unit of the photonic crystal structure in the photonic crystal layer can be a single-lattice unit, a dual-lattice unit, or other forms of multi-lattice unit. A single-lattice photonic crystal structure has a single shape, such as circular or elliptical. A dual-lattice photonic crystal structure includes two different shapes, such as both circular and elliptical photonic crystal structures. Currently, the development of photonic crystal layers for surface-emitting lasers (SSELS) focuses primarily on single-lattice and dual-lattice structures. However, these single-lattice and dual-lattice SSELS still require improvement in terms of single-mode stability, beam quality, power output, and wavelength control.

[0053] To address the technical problems involved in the related technologies, this disclosure provides a photonic crystal surface-emitting laser, which includes a photonic crystal layer with three lattice units. Compared with single-lattice units and dual-lattice units, the three lattice units contained therein are superior in terms of single-mode stability, beam quality, power output and wavelength control.

[0054] As attached Figure 1 - Appendix Figure 4 As shown, the photonic crystal layer includes a photonic crystal layer substrate 100 and a plurality of three-lattice units 200 arranged in an array on the photonic crystal layer substrate 100. It should be noted that the refractive index of the three-lattice units 200 is different from the refractive index of the photonic crystal layer substrate 100.

[0055] The three-lattice unit 200 includes a first photonic crystal structure 201 and two second photonic crystal structures 202. The geometric center of the first photonic crystal structure 201 and the geometric centers of the two second photonic crystal structures 202 are combined to form a triangle. The projection shape of the first photonic crystal structure 201 on the plane parallel to the photonic crystal layer is circular, and the projection shape of the second photonic crystal structure 202 on the plane parallel to the photonic crystal layer is elliptical, triangular, or a non-circular shape with central symmetry and more than 3 sides.

[0056] For example, the triangles mentioned above can be equilateral triangles, isosceles triangles, or, of course, non-isosceles triangles. The centrally symmetric non-circular shapes with more than 3 sides mentioned above can be rectangles, squares, rhombuses, or regular polygons with more than or equal to 5 sides. It should be noted that the two second photonic crystal structures 202 have the same material composition, shape, and size.

[0057] The photonic crystal surface-emitting laser provided in this disclosure employs a three-lattice photonic crystal structure. Compared to single-lattice and dual-lattice photonic crystal structures, multiple three-lattice units are arranged in a periodic array for coordinated control. On one hand, this allows for precise control of the photonic crystal's bandgap characteristics, enhancing the ability to confine optical modes and achieving superior mode control and single-mode stability. On the other hand, it facilitates the formation of multiple Bragg scattering mechanisms, improving the quality factor of the resonant cavity. Furthermore, it allows for more flexible beam control by optimizing lattice symmetry and adjusting the parameters of the three lattices, resulting in beams with low divergence angles and high directionality. Moreover, the three-lattice photonic crystal structure not only supports single-mode operation with a larger emission area but also more easily disperses thermal stress, achieving high power output and thermal management. Finally, by adjusting the lattice constant or material composition of the three-lattice photonic crystal structure, wavelength tuning can be achieved over a wider spectral range (e.g., from near-infrared to visible light).

[0058] It is evident that the three-lattice PCSEL, through multi-dimensional photonic bandgap collaborative design, outperforms traditional single / double-lattice PCSELs in terms of single-mode stability, beam quality, power output, and wavelength control.

[0059] Specifically, the three-lattice unit comprises a circular first photonic crystal structure 201 and two identical non-circular second photonic crystal structures 202. The second photonic crystal structures 202 are elliptical, triangular, or centrally symmetric non-circular shapes with more than three sides. This combination of circular and non-circular photonic crystal structures forms a three-lattice unit. Compared to a fully isomorphic three-lattice unit (e.g., three circular or three elliptical photonic crystal structures), the symmetry of the circular structure and the anisotropy of the non-circular structure, based on these advantages, firstly, enhances the anisotropic bandgap tuning capability of the laser, expands the bandgap coverage, and further improves single-mode stability. Secondly, it facilitates simultaneous control of the beam divergence angle and its directionality. Furthermore, the different shapes of the photonic crystal structures facilitate anisotropic scattering, forming asymmetric refractive index modulation, which more easily covers complex mode competition scenarios. Finally, by independently adjusting the lattice parameters of the first or second photonic crystal structure, it is easier to achieve finer wavelength tuning or multi-band integration.

[0060] As can be seen, the combined design of circular and non-circular photonic crystal structures involved in this disclosure, through the synergistic effect of symmetric and asymmetric scattering mechanisms, is superior to fully isomorphic photonic crystal structures (such as three circular or three elliptical photonic crystal structures) in terms of single-mode stability, beam control flexibility, wavelength tuning and expansion. This gives the laser provided by this disclosure a significant advantage in scenarios involving directional output, multi-physics field control, or complex integration, with the aim of obtaining an output beam with high uniformity, symmetry, directionality, and focusing.

[0061] In summary, the embodiments disclosed herein expand upon more types of three-lattice photonic crystal surface-emitting lasers. Building upon the aforementioned effects, by adjusting parameters such as the material, shape, size, and arrangement of each photonic crystal structure within the three-lattice unit, the relevant parameters of the emitted beam (e.g., emission wavelength, divergence angle, emission direction, focusing, etc.) and emission power can be further adjusted. This allows the photonic crystal surface-emitting laser to output in a specific output mode and maintain high power density and beam quality (high uniformity, symmetry, directionality, and focusing) even under large-area conditions, further enhancing the adaptability of the photonic crystal surface-emitting laser to different scenarios with high precision and high power requirements.

[0062] See Figure 1 A photonic crystal surface-emitting laser is provided. The photonic crystal layer of the photonic crystal surface-emitting laser includes: a photonic crystal layer substrate 100 and a plurality of periodically arrayed triple lattice units 200 disposed on the photonic crystal layer substrate 100. The refractive index of the triple lattice units 200 is different from that of the photonic crystal layer substrate 100. The triple lattice units 200 include a circular photonic crystal structure 201 and two elliptical photonic crystal structures 202a. The geometric centers of the circular photonic crystal structure 201 and the two elliptical photonic crystal structures 202a are combined to form a triangle.

[0063] Elliptical photonic crystal structure 202a is anisotropic (i.e., has different optical properties in different directions), while circular photonic crystal structure 201 is isotropic. Furthermore, the elliptical photonic crystal structure 202a, based on its major and minor axis design, enables the photonic crystal layer to have stronger localized control over the optical field. This is beneficial for enhancing the photonic bandgap modulation capability of the laser, improving optical field confinement and mode control, controlling the beam divergence angle, improving beam uniformity, and increasing output power.

[0064] In addition, compared with the circular photonic crystal structure 201, which has a relatively simple diameter as the control degree of freedom, the elliptical photonic crystal structure 202a can also have its major axis, minor axis and rotation angle as control degrees of freedom. The geometric parameters of the elliptical photonic crystal structure 202a can be adjusted according to actual needs to flexibly adjust the performance of the photonic crystal layer, so that the laser can adapt to different application scenarios.

[0065] See Figure 2 A photonic crystal surface-emitting laser is provided. The photonic crystal layer of the photonic crystal laser includes a photonic crystal layer substrate 100 and a plurality of periodically arrayed triple lattice units 200 disposed on the photonic crystal layer substrate 100. The refractive index of the triple lattice units 200 is different from that of the photonic crystal layer substrate 100. Each triple lattice unit 200 includes a circular photonic crystal structure 201 and two isosceles triangular photonic crystal structures 202b. The geometric centers of the circular photonic crystal structure 201 and the two isosceles triangular photonic crystal structures 202b are aligned to form a triangle.

[0066] The triangular photonic crystal structure 202b is anisotropic, while the circular photonic crystal structure 201 is isotropic. Furthermore, the sharp angles and edges of the isosceles triangle structure can introduce a stronger light scattering effect, which is also beneficial for enhancing the photonic bandgap control capability of the laser, improving the optical field confinement and mode control, controlling the beam divergence angle, improving the beam uniformity, and enhancing the control of the polarization characteristics of the emitted light.

[0067] In addition, compared with the circular photonic crystal structure 201, which has a relatively simple diameter as the control degree of freedom, the triangular photonic crystal structure 202b can also have its side length, shape, and rotation angle as control degrees of freedom. The geometric parameters of the triangular photonic crystal structure 202b can be adjusted according to actual needs to flexibly adjust the performance of the photonic crystal layer, so that the laser can adapt to different application scenarios.

[0068] See Figure 3 A photonic crystal surface-emitting laser is provided. The photonic crystal layer of the photonic crystal surface-emitting laser includes: a photonic crystal layer substrate 100 and a plurality of periodically arrayed triple lattice units 200 disposed on the photonic crystal layer substrate 100. The refractive index of the triple lattice units 200 is different from that of the photonic crystal layer substrate 100. The triple lattice units 200 include a circular photonic crystal structure 201 and two rectangular photonic crystal structures 202c (or square photonic crystal structures). The geometric center of the circular photonic crystal structure 201 and the geometric center of the two rectangular photonic crystal structures 202c (or square photonic crystal structures) cooperate to form a triangle.

[0069] The rectangular photonic crystal structure 202c (or the square photonic crystal structure) is anisotropic, while the circular photonic crystal structure 201 is isotropic. Furthermore, the edges of the rectangular or square structure can produce a stronger localization effect on the optical field. These advantages are particularly beneficial in enhancing the photonic bandgap control capability of lasers, improving optical field confinement and mode control, controlling beam divergence angle, improving beam uniformity, and enhancing the control of the polarization characteristics of the emitted light.

[0070] In addition, the rectangular photonic crystal structure 202c (or the square photonic crystal structure), compared to the circular photonic crystal structure 201 which only has a single degree of freedom for adjustment based on its diameter, can also have its side length, aspect ratio, and rotation angle as degrees of freedom for adjustment. The geometric parameters of the two rectangular photonic crystal structures 202c (or the square photonic crystal structure) can be adjusted according to actual needs to flexibly adjust the performance of the photonic crystal layer, so that the laser can adapt to different application scenarios.

[0071] See Figure 4 A photonic crystal surface-emitting laser is provided. The photonic crystal layer of the photonic crystal laser includes a photonic crystal layer substrate 100 and a plurality of periodically arrayed triple lattice units 200 disposed on the photonic crystal layer substrate 100. The refractive index of the triple lattice units 200 is different from the refractive index of the photonic crystal layer substrate 100. Each triple lattice unit 200 includes a circular photonic crystal structure 201 and two regular polygonal photonic crystal structures 202d. Figure 4 An example is given (a regular pentagon), where the geometric center of the circular photonic crystal structure 201 and the geometric centers of the two regular polygonal photonic crystal structures 202d combine to form a triangle.

[0072] The regular polygonal photonic crystal structure 202d is anisotropic, while the circular photonic crystal structure 201 is isotropic. Furthermore, the edges of the regular polygonal structure can produce a stronger localization effect on the optical field. These advantages are more beneficial in enhancing the photonic bandgap control capability of lasers, improving optical field confinement and mode control, controlling beam divergence angle, improving beam uniformity, and enhancing the control of polarization characteristics of emitted light.

[0073] In addition, compared with the circular photonic crystal structure 201, which has a relatively simple diameter as the control degree of freedom, the regular polygonal photonic crystal structure 202d can also be used as the control degree of freedom for its side length and rotation angle. The geometric parameters of the regular polygonal photonic crystal structure 202d can be adjusted according to actual needs to flexibly adjust the performance of the photonic crystal layer, so that the laser can adapt to different application scenarios.

[0074] The photonic crystal surface-emitting laser disclosed herein has a plurality of three-lattice units arranged in a periodic array. In some examples, the spacing between the geometric centers of any two adjacent three-lattice units can be made the same.

[0075] For any of the aforementioned photonic crystal surface-emitting lasers, as shown in the appendix... Figure 5 As shown (illustrating that the second photonic crystal structure 202 has an elliptical shape), along the plane parallel to the direction of the photonic crystal layer, the coordinates of the geometric center of the first photonic crystal structure 201 are the reference coordinates (x0, y0), and the coordinates of the geometric centers of the two second photonic crystal structures 202 are (x1, y1) and (x2, y2), respectively. The coordinates of the geometric centers of the first and second photonic crystal structures 201 can satisfy any one of conditions one through five, and any one of conditions six through ten.

[0076] (Condition 1): x0 is less than both x1 and x2; (Condition 2): x0 is greater than both x1 and x2; (Condition 3): x0 is greater than one of x1 and x2 and less than the other of x1 and x2; (Condition 4): x0 is equal to one of x1 and x2 and less than the other of x1 and x2; (Condition 5): x0 is equal to one of x1 and x2 and greater than the other of x1 and x2; (Condition 6): y0 is less than both y1 and y2; (Condition 7): y0 is greater than both y1 and y2; (Condition 8): y0 is greater than one of y1 and y2 and less than the other of y1 and y2; (Condition 9): y0 is equal to one of y1 and y2 and less than the other of y1 and y2; (Condition 10): y0 is equal to one of y1 and y2 and greater than the other of y1 and y2.

[0077] For example, the coordinates of the geometric center of the first photonic crystal structure and the coordinates of the geometric center of the second photonic crystal structure can adopt any of the following schemes: simultaneously satisfying conditions one and six; simultaneously satisfying conditions one and seven; simultaneously satisfying conditions one and eight; simultaneously satisfying conditions one and nine; simultaneously satisfying conditions one and ten; simultaneously satisfying conditions two and six; simultaneously satisfying conditions two and seven; simultaneously satisfying conditions two and eight; simultaneously satisfying conditions two and nine; simultaneously satisfying conditions two and ten; simultaneously satisfying conditions three and six; simultaneously satisfying conditions three and seven; simultaneously satisfying conditions three and eight; simultaneously satisfying conditions three and nine; simultaneously satisfying conditions three and ten; simultaneously satisfying conditions four and six; simultaneously satisfying conditions four and seven; simultaneously satisfying conditions four and eight; simultaneously satisfying conditions four and nine; simultaneously satisfying conditions four and ten; simultaneously satisfying conditions five and six; simultaneously satisfying conditions five and seven; simultaneously satisfying conditions five and eight; simultaneously satisfying conditions five and nine; simultaneously satisfying conditions five and ten.

[0078] By adjusting the coordinates of the geometric center of the first photonic crystal structure and the geometric center of the second photonic crystal structure, the photonic bandgap characteristics and polarization characteristics, light field distribution and mode, beam quality and beam direction, and light output power of the photonic crystal layer can be controlled, allowing for adaptive selection according to actual needs.

[0079] For example, when condition one is met, with the first photonic crystal structure located to the left of the two second photonic crystal structures, the optical field may be more strongly coupled on the right side and relatively weaker on the left. When condition two is met, with the first photonic crystal structure located to the right of the two second photonic crystal structures, the optical field may be more strongly coupled on the left side and relatively weaker on the right. When condition three is met, the optical field may be more strongly localized in the region between the first and second photonic crystal structures. When conditions four or five are met, the optical field may be more strongly localized in the region closer to one of the second photonic crystal structures.

[0080] When condition six is ​​met, the first photonic crystal structure is located below the two second photonic crystal structures, and the optical field may be more strongly coupled in the upper region and relatively weaker in the lower region. When condition seven is met, the first photonic crystal structure is located above the two second photonic crystal structures, and the optical field may be more strongly coupled in the lower region and relatively weaker in the upper region. When condition eight is met, the optical field may be more strongly localized in the region between the first and second photonic crystal structures. When conditions nine or ten are met, the optical field may be more strongly localized in the region close to one of the second photonic crystal structures.

[0081] In some implementations, the light field can be more strongly coupled in a specific region by adjusting the coordinate positions of the first photonic crystal structure and the two second photonic crystal structures, thereby enhancing the confinement effect of the light field in that specific region.

[0082] For any of the aforementioned photonic crystal surface-emitting lasers, in some embodiments, the distances between the geometric center of the first photonic crystal structure and the geometric centers of the two second photonic crystal structures are defined as S1 and S2, respectively, and the distance between the geometric centers of the two second photonic crystal structures is defined as S3. S1, S2, and S3 satisfy one of the following conditions 1 to 5: Condition 1: S1 and S2 are the same or different and both are greater than S3; Condition 2: S1 and S2 are the same or different and both are less than S3; Condition 3: S1, S2, and S3 are the same; Condition 4: One of S1 and S2 is less than or equal to S3, and the other is greater than S3; Condition 5: One of S1 and S2 is greater than or equal to S3, and the other is less than S3.

[0083] By adjusting the values ​​of S1, S2, and S3, the photonic bandgap and polarization characteristics, optical field distribution and mode, beam quality and beam direction, and optical output power of the photonic crystal layer can be controlled, allowing for adaptive selection based on actual needs.

[0084] For example, when condition 1 is met, the spacing between the first photonic crystal structure and the two second photonic crystal structures is relatively large, while the spacing between the two second photonic crystal structures is relatively small, which is beneficial for forming strong coupling along the y-axis. When condition 2 is met, the spacing between the two second photonic crystal structures is relatively large, while the spacing between the first photonic crystal structure and the second photonic crystal structure is relatively small, which is beneficial for the laser to output a beam with narrow linewidth, high power, and narrow divergence angle. When condition 3 is met, the three lattice units have high symmetry, which is beneficial for achieving a uniform light field distribution and stable laser output, and also for supporting multi-directional coupling. When conditions 4 or 5 are met, the coupling characteristics of the photonic crystal structure differ in different directions, causing the light field distribution to be biased towards a specific direction.

[0085] In some implementation schemes, such as the appendix Figure 1 As shown, both second photonic crystal structures can be elliptical in shape. Experiments have confirmed that the combination of a circular photonic crystal structure and two elliptical photonic crystal structures is more advantageous for lasers to output beams with narrow linewidth, high power, and narrow divergence angle.

[0086] For the second photonic crystal structure being elliptical, the coordinates of the geometric centers of the first and second photonic crystal structures satisfy the aforementioned condition one (x0 is less than both x1 and x2) and condition ten (y0 is equal to one of y1 and y2 and greater than the other of y1 and y2).

[0087] This configuration facilitates the output of a narrow-linewidth, high-power, and narrow-divergence beam from a photonic crystal surface-emitting laser, even enabling the production of robust Gaussian beams. Furthermore, it improves the laser's power utilization rate, addressing the technical challenge of low power utilization in related technologies. Power utilization rate refers to the ratio of the laser's output power to its input power.

[0088] Furthermore, the distances between the geometric center of the first photonic crystal structure and the geometric centers of the two second photonic crystal structures satisfy that S1 and S2 are the same or different and both are less than S3, which is more advantageous for promoting the output of a laser beam with narrow linewidth, high power and narrow divergence angle.

[0089] For the above implementation scheme, the circular first photonic crystal structure and the elliptical second photonic crystal structure can also satisfy any one of the following conditions a to c: Condition a: The diameter of the first photonic crystal structure is greater than the minor axis and less than the major axis of the second photonic crystal structure; Condition b: The diameter of the first photonic crystal structure is greater than the major axis of the second photonic crystal structure; Condition c: The diameter of the first photonic crystal structure is less than the minor axis of the second photonic crystal structure.

[0090] When condition a is met, it facilitates a wide bandgap and strong feedback, promotes stable single-mode output, and improves beam quality and output efficiency. For example, it can produce a robust Gaussian spot. When condition b is met, it tends to achieve a narrow bandgap and weak feedback, which is beneficial for multimode output. When condition c is met, it facilitates multimode output and has polarization sensitivity, making it suitable for tunable lasers, spectral analysis, and other applications. The appropriate size conditions can be selected based on actual needs. For example, to obtain a Gaussian spot and high power utilization, the diameter of the first photonic crystal structure can be larger than the minor axis and smaller than the major axis of the second photonic crystal structure.

[0091] The arrangement of the elliptical second photonic crystal structures can be selected according to actual needs, making the laser suitable for different application scenarios. In some implementations, the elliptical second photonic crystal structures can satisfy any one of the following conditions d to f: Condition d: The two major axes of the two second photonic crystal structures are parallel (see...). Figure 1 Condition e: The two minor axes of the two second photonic crystal structures are parallel; Condition f: The major axis of second photonic crystal structure a is parallel to the minor axis of second photonic crystal structure b, or the minor axis of second photonic crystal structure a is parallel to the major axis of second photonic crystal structure b. Here, the parallelism between axes mentioned above refers to maintaining parallelism in the distribution directions of the two second photonic crystal structures.

[0092] For example, when condition d is met, the three-lattice unit has high symmetry, which is beneficial for producing a narrow-linewidth, high-power, and narrow-divergence beam from the laser, and it is also easier to obtain a robust Gaussian spot. When condition e is met, the divergence angle of the laser beam is usually asymmetrical, and the photonic bandgap may become narrower or split, making it suitable for scenarios with less stringent beam shape requirements but requiring a certain wavelength tuning capability, such as spectral analysis and low-coherence illumination. When condition f is met, the laser can support multi-mode output. Therefore, the arrangement of the elliptical second photonic crystal structure can be selected according to actual needs, making the laser suitable for different applications. For example, to obtain a Gaussian spot and higher power utilization, the two major axes of the two second photonic crystal structures can be made parallel.

[0093] Of course, the following implementation scheme is not excluded: the major axis and minor axis of the second photonic crystal structure a are not parallel to either the major axis and minor axis of the second photonic crystal structure b, so that the laser can achieve a specific light output mode under this condition.

[0094] For example, this disclosure provides a photonic crystal surface-emitting laser, wherein the second photonic crystal structure is elliptical, and the first photonic crystal structure with a circular shape and the second photonic crystal structure with an elliptical shape simultaneously satisfy the following conditions: the coordinates of the geometric centers of the first photonic crystal structure and the second photonic crystal structure satisfy: (1) x0 is less than both x1 and x2, and y0 is equal to one of y1 and y2 and greater than the other of y1 and y2. (2) S1 and S2 are the same or different and both are less than S3. (3) The diameter of the first photonic crystal structure is less than the major axis dimension of the second photonic crystal structure and greater than the minor axis dimension of the second photonic crystal structure. (4) The two major axes of the two second photonic crystal structures are parallel.

[0095] This approach facilitates the achievement of a wide bandgap and strong feedback, enabling stable single-mode output, thereby improving beam quality and output efficiency. It allows the laser to output a beam with narrow linewidth, high power, and narrow divergence angle, thus obtaining a robust Gaussian spot with a power utilization rate of at least 80%.

[0096] Furthermore, for the case where the distance between the geometric centers of any two adjacent three-lattice units in the laser is the same, the distance between the geometric centers of any two adjacent three-lattice units is defined as w. Along the plane parallel to the direction of the photonic crystal layer, the coordinates of the geometric center of the first photonic crystal structure are (0.1-0.2, 0.5-0.8)w, the coordinates of the geometric centers of the two second photonic crystal structures are (0.2-0.5, 0.1-0.2)w and (0.5-0.8, 0.5-0.8)w respectively, the diameter of the first photonic crystal structure is 0.1w-0.2w, the major axis dimension of the second photonic crystal structure is 0.1w-0.5w, and the minor axis dimension of the second photonic crystal structure is 0.05w-0.15w.

[0097] For the coordinates of the geometric center of the first photonic crystal structure, the x-axis value can be any one of the following values ​​or any interval consisting of any two of the following values: 0.1w, 0.11w, 0.12w, 0.13w, 0.14w, 0.15w, 0.16w, 0.17w, 0.18w, 0.19w, 0.20w, etc., and the y-axis value can be any one of the following values ​​or any interval consisting of any two of the following values: 0.5w, 0.51w, 0.52w, 0.53w, 0.54w, 0.55w, 0.5 The coordinates of the geometric center of the first photonic crystal structure can be any combination of the above x-axis and y-axis values, such as 6w, 0.57w, 0.58w, 0.59w, 0.60w, 0.61w, 0.62w, 0.63w, 0.64w, 0.65w, 0.66w, 0.67w, 0.68w, 0.69w, 0.70w, 0.71w, 0.72w, 0.73w, 0.74w, 0.75w, 0.76w, 0.77w, 0.78w, 0.79w, and 0.80w.

[0098] For the coordinates of the geometric center of one of the second photonic crystal structures, the x-axis value can be any of the following values ​​or an interval consisting of any two of the following values: 0.2w, 0.21w, 0.22w, 0.23w, 0.24w, 0.25w, 0.26w, 0.27w, 0.28w, 0.29w, 0.30w, 0.31w, 0.32w, 0.33w, 0.34w, 0.35w, 0.36w, 0.37w, 0.38w, 0.39w, 0.4w, 0.41w, 0.4 The x-axis values ​​can be 2w, 0.43w, 0.44w, 0.45w, 0.46w, 0.47w, 0.48w, 0.49w, 0.5w, etc., and the y-axis values ​​can be any of the following values ​​or any interval consisting of any two of the following values: 0.1w, 0.11w, 0.12w, 0.13w, 0.14w, 0.15w, 0.16w, 0.17w, 0.18w, 0.19w, 0.20w, etc. The coordinates of the geometric center of the second photonic crystal structure can be a combination of any of the above x-axis values ​​and any of the above y-axis values.

[0099] For the coordinates of the geometric center of the other second photonic crystal structure, the x-axis value can be any of the following values ​​or any interval consisting of any two of the following values: 0.5w, 0.51w, 0.52w, 0.53w, 0.54w, 0.55w, 0.56w, 0.57w, 0.58w, 0.59w, 0.60w, 0.61w, 0.62w, 0.63w, 0.64w, 0.65w, 0.66w, 0.67w, 0.68w, 0.69w, 0.70w, 0.71w, 0.72w, 0.73w, 0.74w, 0.75w, 0.76w, 0.77w, 0.78w, 0.79w, 0.80w, etc., and the y-axis value can be... The following values ​​or any ranges of values ​​are used: 0.5w, 0.51w, 0.52w, 0.53w, 0.54w, 0.55w, 0.56w, 0.57w, 0.58w, 0.59w, 0.60w, 0.61w, 0.62w, 0.63w, 0.64w, 0.65w, 0.66w, 0.67w, 0.68w, 0.69w, 0.70w, 0.71w, 0.72w, 0.73w, 0.74w, 0.75w, 0.76w, 0.77w, 0.78w, 0.79w, 0.80w, etc. The coordinates of the geometric center of the second photonic crystal structure can be any combination of the above x-axis and y-axis values.

[0100] The diameter of the first photonic crystal structure can be any one of the following values ​​or any range of two values: 0.1 W, 0.11 W, 0.12 W, 0.13 W, 0.14 W, 0.15 W, 0.16 W, 0.17 W, 0.18 W, 0.19 W, 0.20 W, etc. The major axis dimension of the second photonic crystal structure can be any one of the following values ​​or any range of two values: 0.1 W, 0.11 W, 0.12 W, 0.13 W, 0.14 W, 0.15 W, 0.16 W, 0.17 W, 0.18 W, etc. w, 0.19w, 0.20w, 0.21w, 0.22w, 0.23w, 0.24w, 0.25w, 0.26w, 0.27w, 0.28w, 0.29w, 0.30w, 0.31w, 0.32w, 0.33w, 0.34 w, 0.35w, 0.36w, 0.37w, 0.38w, 0.39w, 0.4w, 0.41w, 0.42w, 0.43w, 0.44w, 0.45w, 0.46w, 0.47w, 0.48w, 0.49w, 0.5w, etc. The short axis dimension of the second photonic crystal structure can be any of the following values ​​or any range of two values: 0.05w, 0.06w, 0.07w, 0.08w, 0.09w, 0.1w, 0.11w, 0.12w, 0.13w, 0.14w, 0.15w, etc.

[0101] Based on the above technical solution, the photonic crystal surface-emitting laser can emit a Gaussian spot with a divergence angle of less than 1 degree * 1 degree, and the power utilization rate of the photonic crystal surface-emitting laser reaches more than 90%.

[0102] Furthermore, along the plane parallel to the direction of the photonic crystal layer, the coordinates of the geometric center of the first photonic crystal structure are (0.1-0.15, 0.6-0.7)w, and the coordinates of the geometric centers of the two second photonic crystal structures are (0.25-0.4, 0.12-0.18)w and (0.55-0.7, 0.55-0.7)w, respectively. The diameter of the first photonic crystal structure is 0.1w-0.15w, the major axis dimension of the second photonic crystal structure is 0.1w-0.3w, and the minor axis dimension of the second photonic crystal structure is 0.05w-0.1w.

[0103] Based on the above technical solution, the photonic crystal surface-emitting laser can emit a Gaussian spot with a divergence angle of less than 0.2 degrees * 0.2 degrees, and the power utilization rate of the photonic crystal surface-emitting laser reaches 95%, or even more than 99%.

[0104] In this embodiment, multiple three-lattice units can be arranged in a periodically arranged array to precisely and controllably regulate the light emission performance of the photonic crystal layer, thereby optimizing the light field distribution and emission characteristics of the laser. Some suitable arrays composed of multiple three-lattice units include square arrays (rectangular arrays, square arrays), circular arrays, elliptical arrays, rhomboid arrays, and regular polygon arrays with more than or equal to 5 sides (e.g., regular pentagonal arrays, regular hexagonal arrays), which can be selected according to actual needs.

[0105] The above provides an exemplary description of the structural arrangement of the photonic crystal layer in a photonic crystal surface-emitting laser, as shown in the attached figure. Figure 6 As shown, in addition to the photonic crystal layer 006, the photonic crystal surface-emitting laser also includes an n-type electrode 001, an n-type cladding layer 002, a multi-quantum well layer 003, an electron blocking layer 004, a first gradient layer 005, a regrowth layer 007, a second gradient layer 008, a p-type cladding layer 009, a third gradient layer 0010, and a p-type contact layer 0011. The n-type electrode 0011, n-type cladding 002, multiple quantum well layer 003, electron blocking layer 004, first gradient layer 005, photonic crystal layer 006, regeneration layer 007, second gradient layer 008, p-type cladding 009, third gradient layer 0010, p-type contact layer 0011, and p-type electrode 0012 are stacked sequentially.

[0106] The function of the n-type cladding 002 is to provide an electronic path for electrical injection, while restricting the diffusion of charge carriers in the vertical direction, confining the charge carriers within the active region (quantum well), and improving the utilization rate of charge carriers. The material and thickness of the n-type cladding 002 are selected according to its function and actual application scenario.

[0107] The role of the multi-quantum well layer 003 is to serve as an active region where electrons and holes recombine to generate photons. This effectively restricts the movement of charge carriers in a two-dimensional direction, thereby improving luminous efficiency. The material and thickness of the multi-quantum well layer 003 are selected according to its function and the actual application scenario.

[0108] The function of the electron blocking layer 004 is to prevent electrons from diffusing from the quantum well region to the p-type region, reduce electron leakage, increase the carrier concentration in the quantum well region, and thus improve the efficiency of the laser. The material and thickness of the electron blocking layer 004 are selected according to its function and actual application scenario.

[0109] The function of the first gradient layer 005 is to alleviate lattice mismatch and thermal mismatch between different materials, smooth the band difference and refractive index difference at the interface, and improve the performance and operational reliability of the device. The material and thickness of the first gradient layer 005 are selected according to its function and actual application scenario.

[0110] As mentioned above, the function of photonic crystal layer 006 is to provide a photonic crystal structure. It is a regular optical structure made by periodically arranging media with different refractive indices to form a photonic bandgap, which can block photons of specific frequencies, realize the control and feedback of light, and thus realize surface-emitting laser output. The material and thickness of photonic crystal layer 006 are selected according to its function and actual application scenario.

[0111] The purpose of the regenerated layer 007 is to further optimize the device structure, such as improving the contact and matching between the photonic crystal layer and subsequent layers. The material and thickness of the regenerated layer 007 are selected according to its function and actual application scenario.

[0112] The function of the second gradient layer 008 is to alleviate lattice mismatch and thermal mismatch between different materials, smooth the band difference and refractive index difference at the interface, and improve the performance and operational reliability of the device. The material and thickness of the second gradient layer 008 are selected according to its function and actual application scenario.

[0113] The function of the p-type cladding 009 is to provide a path for electrically injected holes while restricting the diffusion of charge carriers in the vertical direction, confining the charge carriers within the active region (quantum well region), and improving the utilization rate of charge carriers. The material and thickness of the p-type cladding 009 are selected according to its function and actual application scenario.

[0114] The function of the third gradient layer 0010 is to alleviate lattice mismatch and thermal mismatch between different materials, smooth the band difference and refractive index difference at the interface, and improve the performance and operational reliability of the device. The material and thickness of the third gradient layer 0010 are selected according to its function and actual application scenario.

[0115] The function of the p-type contact layer 0011 is to form a good ohmic contact with the metal electrode, reduce contact resistance, improve the electrical performance of the device, and facilitate current injection. The material and thickness of the p-type contact layer 0011 are selected according to its function and actual application scenario.

[0116] The multi-layer design of the photonic crystal surface-emitting laser effectively avoids the shortcomings of EEL and VCSEL, giving it advantages such as surface emission, high output beam power, narrow linewidth, and single-mode output, and the ability to output Gaussian beams under specific conditions.

[0117] The photonic crystal surface-emitting laser provided in this disclosure is applicable to various epitaxial materials such as indium gallium arsenide, aluminum gallium indium arsenide, gallium arsenide, or indium phosphide to generate emitted light in different wavelengths, thereby meeting different application requirements.

[0118] In some examples, the photonic crystal layer substrate is selected from indium gallium arsenide, aluminum gallium indium arsenide, gallium arsenide, or indium phosphide.

[0119] For example, the first gradient layer, photonic crystal layer, regenerated layer, second gradient layer, and multiple quantum well layer can all use the same material system (the specific composition of the materials may differ). For instance, they can all be selected from the aluminum gallium indium arsenide material system. Correspondingly, the n-type cladding and p-type cladding can both be selected from the indium phosphide material system, and the electron blocking layer can be selected from the aluminum indium arsenide material system.

[0120] In this embodiment of the disclosure, the first photonic crystal structure and the two second photonic crystal structures in the photonic crystal layer are air holes or dielectric pillars, and the material of the dielectric pillars is selected from elements, alloys or compounds of Group III-V, II-VI or IV.

[0121] For photonic crystal structures with air holes, the medium inside the hole can be considered as air. This type of structure is suitable for applications requiring high refractive index contrast and wide bandgap. For example, the air hole may penetrate the photonic crystal layer. For photonic crystal structures with dielectric pillars, the hole is filled with a semiconductor material to form a dielectric pillar. This type of structure is suitable for applications requiring medium refractive index contrast and narrow bandgap. The choice between these structures depends on the specific needs.

[0122] For example, some alloys or compounds of Group III-V can be materials such as GaAs, InP, GaN, and AlGaAs; some alloys or compounds of Group II-VI can be materials such as ZnSe, CdTe, and ZnO; and some elements, alloys, or compounds of Group IV can be materials such as Si, Ge, SiC, and SiO2.

[0123] In this embodiment of the disclosure, the longitudinal section of the hole or dielectric pillar containing the photonic crystal structure along the direction perpendicular to the photonic crystal layer can be of uniform width or variable width, depending on the actual requirements. The width referred to here is the dimension along the direction parallel to the photonic crystal layer.

[0124] Regarding the aforementioned technical solutions for photonic crystal surface-emitting lasers, this disclosure provides a typical photonic crystal surface-emitting laser for simulation testing, as shown in the attached figure. Figure 6 As shown, the photonic crystal surface-emitting laser includes, from bottom to top, an n-type electrode 001, an n-type cladding layer 002, a multiple quantum well layer 003, an electron blocking layer 004, a first gradient layer 005, a photonic crystal layer 006, a regeneration layer 007, a second gradient layer 008, a p-type cladding layer 009, a third gradient layer 0010, a p-type contact layer 0011, and a p-type electrode 0012. The material selection and thickness settings for each semiconductor layer can be found in Table 1.

[0125] Table 1

[0126]

[0127] In Table 1, the subscript values ​​in the general chemical formulas of each material represent the atomic percentage of the corresponding element, denoted by In. 0.53 Ga 0.47 Taking As as an example, it means that the ratio of the sum of the number of In atoms and Ga atoms to the number of As atoms is 1:1, and the number of In atoms accounts for 53% of the sum of the number of In atoms and Ga atoms, while the number of Ga atoms accounts for 47% of the sum of the number of In atoms and Ga atoms.

[0128] For photonic crystal layer 006, its multiple three-lattice units cooperate to form a periodically arranged rectangular matrix. The distance between the geometric centers of any two adjacent three-lattice units is the same and defined as w. Each three-lattice unit includes a circular photonic crystal structure and two identical elliptical photonic crystal structures, both of which are air holes (i.e., they are filled with air). The circular and elliptical photonic crystal structures simultaneously satisfy the following condition: the two major axes of the two second photonic crystal structures are parallel. The coordinates of the geometric center of the circular photonic crystal structure are (0.1303, 0.6849)w, and the coordinates of the geometric centers of the elliptical photonic crystal structures are (0.3151, 0.1538)w and (0.6849, 0.6849)w, respectively. The diameter of the circular photonic crystal structure is 0.1303w, the major axis dimension of the elliptical photonic crystal structure is 0.2004w, and the minor axis dimension of the elliptical photonic crystal structure is 0.0847w.

[0129] The photonic crystal surface-emitting laser was simulated and tested using a laser signal transmission simulation system. The test results are shown in [link to test results]. Figure 7 ,Depend on Figure 7 It can be seen that this photonic crystal surface-emitting laser has at least the following advantages:

[0130] (1) Output Gaussian spot: Figure 7A standard Gaussian spot is shown, and the divergence angle of the Gaussian spot is extremely narrow, less than 0.2 degrees * 0.2 degrees.

[0131] (2) Achieving high power utilization: The laser's input power (i.e., total power) is 27.499, its output power is 27.392, its in-plane loss power is 0.107, and its power utilization is 99.61%. It is evident that the laser achieves a power utilization rate of over 99% for its input power. Compared to the maximum power utilization rate of 80% for traditional lasers, the power utilization rate of the laser involved in this embodiment is significantly improved. It should be noted that the power units mentioned above have been normalized and are not shown here again.

[0132] In addition to using the aforementioned photonic crystal surface-emitting laser as a reference laser, this disclosure also provides several other lasers. These lasers all have a process error of less than or equal to 5 nm compared to the reference laser. For example, for a 5 nm process error, the designed diameter of the circle is 5 micrometers, but the actual fabricated diameter is 5 micrometers + / - 5 nanometers. Alternatively, the ideal center position 'a' is at (200 micrometers, 200 micrometers) coordinates, but the actual fabricated center position 'a' is at (200 micrometers + / - 5 nanometers, 200 micrometers + / - 5 nanometers) coordinates. The output performance of these lasers with process errors was tested, with a total of 50 sets of process error tests performed. The test results are shown in [link to test results]. Figure 8 ,Depend on Figure 8 It can be seen that the output performance of these lasers with process errors is almost unaffected by the process errors, and they can still stably output Gaussian beams. Moreover, the divergence angle of the Gaussian beams is always maintained at the expected level of less than 1 degree * 1 degree. This proves that the photonic crystal surface-emitting laser provided in this embodiment has robust characteristics.

[0133] On the other hand, a light source is provided, which includes a printed circuit board and a laser array, the laser array being disposed on the printed circuit board, the laser array including a plurality of any of the above-mentioned photonic crystal surface-emitting lasers.

[0134] The light source provided in this disclosure has all the advantages of the photonic crystal surface-emitting laser described above.

[0135] On another front, a projection device is provided, which includes the aforementioned light source, modulator, and lens. The modulator is used to modulate the light beam emitted by the light source and output a light signal, and the lens is used to transmit the light signal to output a projected image.

[0136] The projection device provided in this disclosure has all the advantages of the photonic crystal surface-emitting laser or light source mentioned above.

[0137] The projection device provided in this disclosure can be applied to a variety of scenarios, including but not limited to: PCSEL projection device or projector, vehicle display device, security monitoring device, home theater, augmented reality and virtual reality device, medical imaging device, etc.

[0138] The above description is only for the purpose of enabling those skilled in the art to understand the technical solutions disclosed herein, and is not intended to limit the scope of this disclosure. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this disclosure should be included within the protection scope of this disclosure.

Claims

1. A photonic crystal surface-emitting laser, characterized in that, The photonic crystal surface-emitting laser includes a photonic crystal layer, which includes a photonic crystal layer substrate and a plurality of three-lattice units arranged in an array on the photonic crystal layer substrate. The three-lattice unit includes a first photonic crystal structure and two second photonic crystal structures, wherein the geometric centers of the first photonic crystal structure and the geometric centers of the two second photonic crystal structures cooperate to form a triangle; Wherein, the projection shape of the first photonic crystal structure on the plane parallel to the photonic crystal layer is circular, and the projection shape of the second photonic crystal structure on the plane parallel to the photonic crystal layer is elliptical, triangular, or a non-circular shape with central symmetry and more than 3 sides.

2. The photonic crystal surface-emitting laser according to claim 1, characterized in that, The centrally symmetric non-circular shape with more than 3 sides is a rectangle, square, rhombus, or a regular polygon with more than or equal to 5 sides.

3. The photonic crystal surface-emitting laser according to claim 1, characterized in that, The second photonic crystal structure is elliptical in shape.

4. The photonic crystal surface-emitting laser according to claim 3, characterized in that, Along the plane parallel to the direction of the photonic crystal layer, the coordinates of the geometric center of the first photonic crystal structure are the reference coordinates (x0, y0), and the coordinates of the geometric centers of the two second photonic crystal structures are (x1, y1) and (x2, y2), respectively. The coordinates of the geometric centers of the first photonic crystal structure and the second photonic crystal structure satisfy the following: x0 is less than both x1 and x2, and y0 is equal to one of y1 and y2 and greater than the other of y1 and y2.

5. The photonic crystal surface-emitting laser according to claim 4, characterized in that, The distances between the geometric center of the first photonic crystal structure and the geometric centers of the two second photonic crystal structures are defined as S1 and S2, respectively, and the distance between the geometric centers of the two second photonic crystal structures is defined as S3. S1, S2 and S3 satisfy the following condition: S1 and S2 are both less than S3.

6. The photonic crystal surface-emitting laser according to claim 4, characterized in that, The diameter of the first photonic crystal structure is larger than the minor axis of the second photonic crystal structure and smaller than the major axis of the second photonic crystal structure.

7. The photonic crystal surface-emitting laser according to claim 6, characterized in that, The two long axes of the two second photonic crystal structures are parallel.

8. The photonic crystal surface-emitting laser according to any one of claims 4-7, characterized in that, The distance between the geometric centers of any two adjacent three-lattice units is defined as w. Along the plane parallel to the direction of the photonic crystal layer, the coordinates of the geometric center of the first photonic crystal structure are (0.1-0.2, 0.5-0.8)w, the coordinates of the geometric centers of the two second photonic crystal structures are (0.2-0.5, 0.1-0.2)w and (0.5-0.8, 0.5-0.8)w respectively, and the diameter of the first photonic crystal structure is 0.1w-0.2w, the major axis dimension of the second photonic crystal structure is 0.1w-0.5w, and the minor axis dimension of the second photonic crystal structure is 0.05w-0.15w.

9. The photonic crystal surface-emitting laser according to claim 8, characterized in that, The coordinates of the geometric center of the first photonic crystal structure are (0.1-0.15, 0.6-0.7)w, and the coordinates of the geometric centers of the two second photonic crystal structures are (0.25-0.4, 0.12-0.18)w and (0.55-0.7, 0.55-0.7)w, respectively. The diameter of the first photonic crystal structure is 0.1w-0.15w, the major axis dimension of the second photonic crystal structure is 0.1w-0.3w, and the minor axis dimension of the second photonic crystal structure is 0.05w-0.1w.

10. The photonic crystal surface-emitting laser according to any one of claims 1-9, characterized in that, The array composed of multiple of the three lattice units includes square arrays, circular arrays, elliptical arrays, rhomboid arrays, and regular polygon arrays with a number of sides greater than or equal to 5.

11. The photonic crystal surface-emitting laser according to any one of claims 1-10, characterized in that, The photonic crystal surface-emitting laser further includes an n-type electrode, an n-type cladding, a multiple quantum well layer, an electron blocking layer, a first gradient layer, a regeneration layer, a second gradient layer, a p-type cladding, a third gradient layer, a p-type contact layer, and a p-type electrode. The n-type electrode, the n-type cladding, the multiple quantum well layer, the electron blocking layer, the first gradient layer, the photonic crystal layer, the regeneration layer, the second gradient layer, the p-type cladding, the third gradient layer, the p-type contact layer, and the p-type electrode are stacked in sequence.

12. The photonic crystal surface-emitting laser according to claim 11, characterized in that, The photonic crystal layer substrate is made of indium gallium arsenide, aluminum gallium indium arsenide, gallium arsenide, or indium phosphide.

13. The photonic crystal surface-emitting laser according to claim 12, characterized in that, The first photonic crystal structure and the two photonic crystal structures are air holes or dielectric pillars, and the material of the dielectric pillars is selected from elements, alloys or compounds of Group III-V, II-VI or IV.

14. A light source, characterized in that, The light source includes a printed circuit board and a laser array, the laser array being disposed on the printed circuit board, and the laser array including a plurality of photonic crystal surface-emitting lasers as described in any one of claims 1-13.

15. A projection device, characterized in that, The projection device includes the light source, modulator, and lens as described in claim 14, wherein the modulator is used to modulate the light beam emitted by the light source and output an optical signal, and the lens is used to transmit the optical signal to output a projected image.

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