A reflection-diffraction hybrid beam array beam splitter

Abstract

The application discloses a reflection-diffraction mixed beam array beam splitter and a beam splitting method, and belongs to the technical field of optical communication, optical computing and optical sensing. The beam splitter comprises at least one beam splitting prism group and a diffraction grating array. The beam splitting prism group is composed of a plurality of prism units which are glued side by side along the beam splitting direction. The glued surfaces of adjacent prisms are coated with beam splitting films with independent parameters, which can split the incident light beam into multiple sub-beams with controllable power and direction. The diffraction grating array comprises sub-grating units corresponding to the sub-beams one by one. The 0th order transmitted light is used to modulate the output power of each beam. The diffraction grating array is a replaceable structure, and the beam splitting ratio of the beam array can be quickly switched. The application can generate a beam array with any direction and any beam splitting ratio, and has the advantages of high integration and low cost.

Description

Technical Field

[0001] This invention relates to the field of diffractive optical element technology, specifically to a reflection-diffraction hybrid beam array splitter. Background Technology

[0002] With the rapid development of optical computing, optical sensing, and optical interconnect technologies, beam array generating devices have become key optical components in systems such as parallel optical testing, array illumination, and multi-channel optical communication. In practical applications, it is often required that each sub-beam of the beam array has a differentiated emission direction and power distribution to accurately match optoelectronic devices in different spatial locations, which places high demands on the design freedom and adaptability of the devices.

[0003] Currently, the mainstream beam splitting schemes are mainly divided into three categories, all of which have insurmountable technical limitations: The first type is diffractive optical elements (DOEs). These devices rely on the diffraction effect of micro- and nano-structures to achieve beam splitting, generating multi-beam arrays with almost arbitrary energy distributions. They are also small in size and highly integrated. However, the angle of the emitted beam strictly follows the grating diffraction equation, determined by the grating period and the operating wavelength. It is impossible to independently design the emission direction of each sub-beam, making it difficult to achieve arbitrary beam deflection or collimated parallel output. Furthermore, the beam splitting ratio is fixed after the device is fabricated, preventing flexible switching based on application requirements and limiting its applicability.

[0004] The second type is the traditional passive prism beam splitter. Conventional beam splitters are mostly cubic structures, capable of only achieving basic beam splitting from 1 to 2; even the few multi-beam splitters can only output beams with a fixed splitting ratio and a fixed exit angle, and cannot independently adjust the power and direction of each sub-beam. If parameters need to be adjusted, the prism must be redesigned and manufactured, resulting in a long development cycle and high modification costs.

[0005] The third category is active beam splitters such as spatial light modulators. These devices can adjust the beam splitting ratio and beam direction in real time via electronic control, offering high flexibility. However, they are bulky, have low system integration, and are expensive, making them unsuitable for miniaturized optical systems and mass production scenarios with strict requirements on size and cost.

[0006] In summary, existing technologies cannot simultaneously meet the requirements of arbitrary beam pointing design, arbitrary beam splitting ratio configuration, rapid beam splitting ratio switching, and high integration at low cost, thus becoming a technical bottleneck restricting the performance improvement of parallel optical systems. Summary of the Invention

[0007] This invention provides a reflection-diffraction hybrid beam array splitter, which can solve the technical problem that current diffractive optical elements can only emit beams at a fixed angle and the beam splitting ratio of sub-beams is fixed, resulting in low applicability.

[0008] To achieve the above objectives, in a first aspect, the present invention provides the following technical solution: a reflection-diffraction hybrid beam array splitter, comprising at least one beam-splitting prism group and a diffraction grating array in sequence along the optical path propagation direction; The beam splitter prism assembly includes several prism units bonded side by side along the beam splitting direction. The bonding surfaces of two adjacent prism units are coated with a beam splitting film. The transmittance and reflectance of each beam splitting film are set independently, and the angle between each beam splitting film and the beam splitting direction is set independently. After the incident beam is transmitted and reflected sequentially by each beam-splitting membrane, it forms multiple sub-beams arranged along the beam-splitting direction; The diffraction grating array includes multiple sub-grating units, each corresponding to a sub-beam. Each sub-beam is independently incident on a sub-grating unit. The sub-grating unit is used to diffract part of the energy of the incident sub-beam to higher diffraction orders, retaining the 0th order transmitted light as the effective output beam. The final power of the corresponding effective output beam is independently modulated by the 0th order transmittance of each sub-grating unit. The diffraction grating array is a replaceable structure. By replacing the diffraction grating array with different 0th order transmittance distributions, the overall beam splitting ratio of the output beam array can be switched.

[0009] Preferably, the beam splitter prism group includes a first beam splitter prism group and a second beam splitter prism group arranged sequentially along the optical path. The beam splitting direction of the first beam splitter prism group is a first direction x, and the beam splitting direction of the second beam splitter prism group is a second direction y. The first direction x and the second direction y are perpendicular to each other. The front-to-back arrangement order of the first beam splitter prism group and the second beam splitter prism group along the optical path can be interchanged. After two stages of beam splitting, a two-dimensional beam array of M rows and N columns is formed. The diffraction grating array is correspondingly set as a two-dimensional array containing M×N sub-grating units.

[0010] Preferably, the incident side of the beam splitter prism group is further provided with an incident polarization passivation device, which is used to control the polarization state of the incident beam.

[0011] Preferably, the output side of the diffraction grating array is further provided with an output polarization passivation device, which is used to control the polarization state of the effective output beam.

[0012] Preferably, the beam splitter is a dielectric film or a metal film. The dielectric film achieves transmittance and reflectance control by alternately depositing multiple thin films of high and low refractive index materials, while the metal film achieves transmittance and reflectance control by adjusting the film thickness.

[0013] Preferably, in the same beam-splitting prism group, the angles between each beam-splitting membrane and the beam-splitting direction are equal, and the output sub-beams are parallel to each other, forming a collimated beam array.

[0014] Preferably, in the same beam-splitting prism group, at least one beam-splitting membrane has an angle different from the beam-splitting direction than the other beam-splitting membranes, and the output sub-beams are non-parallel beams.

[0015] Preferably, the diffraction grating array includes N rows of first beam-splitting regions and M rows of second beam-splitting regions. The first beam-splitting regions extend along a first direction x, and the second beam-splitting regions extend along a second direction y. The first beam-splitting regions and the second beam-splitting regions are intersected to form sub-grating units.

[0016] Preferably, the sub-grating unit is a surface relief grating or an embedded volume grating, and the 0th order transmittance of each sub-grating unit is independently set by adjusting the grating phase modulation depth, scribing depth or grating period.

[0017] In a second aspect, the present invention also provides a beam array splitting method, which employs a reflection-diffraction hybrid beam array splitter as described in the first aspect, including the following steps: S1, prism beam splitting: the incident beam is incident on a beam splitting prism group, and after successive transmission and reflection through multiple layers of beam splitting films, it is split into multiple sub-beams arranged along the beam splitting direction. Among them, the first sub-beam is the transmitted light that passes through the first beam-splitting film, and the output power satisfies: ; In the formula, The total power of the incident beam. The transmittance of the first beam splitter layer; The i-th sub-beam is a beam that, after being reflected by the first beam-splitting layer, passes sequentially through the second to (i-1)-th beam-splitting layers, and is then reflected by the i-th beam-splitting layer before exiting. The exit power satisfies the following: ; In the formula, The reflectivity of the first beam-splitting film. The transmittances of the beam splitters are, in order, from the 2nd to the (i-1th)th layers. Let be the reflectivity of the i-th beam splitter layer; The initial power of each sub-beam is independently allocated by presetting the transmittance and reflectance of each beam splitter; the exit angle between two adjacent sub-beams satisfies: ; In the formula, Let be the angle between the i-th beam-splitting layer and the beam-splitting direction. The angle between the (i-1)th beam splitter and the beam splitting direction is used to independently control the angle between the output direction of each sub-beam and the adjacent sub-beam by presetting the tilt angle of each beam splitter. S2, Diffraction Amplitude Modulation: Each sub-beam after splitting is incident on a corresponding sub-grating unit. The diffraction effect of the sub-grating unit is used to deflect part of the beam energy to higher diffraction orders, retaining only the 0th order transmitted light as the effective output. The final power of the corresponding effective beam is modulated by the 0th order transmittance of each sub-grating unit. S3, Beam splitting ratio switching: Replace the diffraction grating array with a different 0th order transmittance distribution, and adjust the overall beam splitting ratio of the output beam array without changing the beam splitting prism group.

[0018] Compared with the prior art, the technical solution of the present invention can achieve the following technical effects: 1. High degree of freedom in beam pointing design. By independently setting the tilt angle of each beam splitter, the emission direction of each sub-beam can be flexibly adjusted to generate parallel collimated arrays or non-parallel arrays with different angles, breaking through the limitation of fixed diffraction angles of traditional diffractive optical elements and adapting to diverse optical path layout requirements.

[0019] 2. Precise and flexible beam splitting ratio configuration. The transmittance and reflectance of each beam splitter can be designed independently, enabling precise one-dimensional or two-dimensional beam arrays with arbitrary power distribution to meet the differentiated power requirements of different channels, with high power allocation accuracy.

[0020] 3. The beam splitting ratio can be quickly switched. It adopts a replaceable diffraction grating array and uses the 0th order transmission characteristics of the grating to achieve passive power modulation. The overall beam splitting ratio can be switched without modifying the prism body. The switching cost is low and the efficiency is high, which solves the pain point of fixed parameters in traditional passive beam splitters.

[0021] 4. High device integration and strong stability. Adopting a fully passive glass structure with no electronic control components, it is small in size, has strong anti-interference capabilities, and can be mass-produced through optical cold processing and micro / nano processes. This results in low production costs, good performance consistency within the same batch, and wide applicability to the application needs of miniaturized optical systems. Attached Figure Description

[0022] Figure 1 This is a schematic diagram of the overall beam array splitting device according to an embodiment of the present invention; Figure 2 This is a schematic diagram of the propagation of a light beam in a prism array according to an embodiment of the present invention; Figure 3 This is a schematic diagram of the first and second beam-splitting regions of the diffraction grating array according to an embodiment of the present invention; Figure 4 This is a schematic diagram of a diffraction grating array according to an embodiment of the present invention; Figure 5 This is a schematic diagram of beam diffraction propagation according to an embodiment of the present invention; Figure 6 This is a schematic diagram of the light field distribution of the first planar sub-beam according to an embodiment of the present invention; Figure 7 This is a schematic diagram of the light field distribution of the second planar sub-beam in an embodiment of the present invention.

[0023] Reference numerals: 1. First beam-splitting prism group; 2. Second beam-splitting prism group; 3. Diffraction grating array; 4. Incident polarization purification device; 5. Outgoing polarization purification device; 6. Beam-splitting film; 8. Incident beam; 11. Prism unit; 31. First beam-splitting region; 32. Second beam-splitting region; 33. Sub-grating unit; 71. Main beam; 72. Second beam; 81. Sub-beam; x, First direction; y, Second direction; A, First plane; B, Second plane. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention.

[0025] like Figure 1-7 As shown, in order to solve the technical problem that current diffractive optical elements can only emit beams at fixed angles and the beam splitting ratio of sub-beams is fixed and has low applicability, the present invention provides the following technical solution: a reflection-diffraction hybrid beam array beam splitter, which includes at least one beam splitting prism group and a diffraction grating array 3 in sequence along the optical path propagation direction; The beam splitter prism group includes several prism units 11 bonded together side by side along the beam splitting direction. The bonding surfaces of two adjacent prism units 11 are coated with a beam splitting film 6. The transmittance and reflectance of each beam splitting film 6 are set independently, and the angle between each beam splitting film 6 and the beam splitting direction is set independently. After the incident beam 8 is transmitted and reflected sequentially by each beam splitter, it forms a multi-path sub-beam 81 arranged along the beam splitting direction; The diffraction grating array 3 includes multiple sub-grating units 33, each corresponding to one of the sub-beams 81. Each sub-beam is independently incident on a sub-grating unit 33. The sub-grating unit 33 is used to diffract a portion of the energy of the incident sub-beam 81 to higher diffraction orders, retaining the 0th order transmitted light as the effective output beam. The final power of the corresponding effective output beam is independently modulated by the 0th order transmittance of each sub-grating unit 33. The diffraction grating array 3 is a replaceable structure; by replacing it with a diffraction grating array 3 that has a different 0th order transmittance distribution, the output beam array can be switched. The overall beam splitting ratio of the array is high. The beam splitting prism group adopts an integrated structure of multiple prism units bonded side by side and coated on the bonded surface. A single prism group can split a single beam into multiple beams. Compared with discrete beam splitting elements, the optical path is more compact, the size is smaller, and the assembly error is lower. The transmittance and reflection ratio of each beam splitting film are set independently, and the power distribution ratio can be designed separately for each sub-beam to realize beam arrays with arbitrary beam splitting ratios and adapt to the power requirements of different scenarios. Passive power attenuation is achieved by utilizing the grating diffraction effect, without the need for an electrical control structure. The device has strong stability and high reliability, and is suitable for use in complex working conditions.

[0026] The technical solution of this embodiment combines two heterogeneous optical architectures, namely prism reflection beam splitting and grating diffraction amplitude modulation, in a cascaded manner. This retains the advantages of flexible prism pointing and high degree of freedom in beam splitting ratio design, while also making up for the defects of fixed beam splitting ratio in passive prisms. It realizes switchable beam splitting ratio under a fully passive architecture and solves the main problems of the prior art.

[0027] In this embodiment, the beam-splitting prism group includes a first beam-splitting prism group 1 and a second beam-splitting prism group 2 arranged sequentially along the optical path. The beam-splitting direction of the first beam-splitting prism group 1 is a first direction x, and the beam-splitting direction of the second beam-splitting prism group 2 is a second direction y. The first direction x and the second direction y are perpendicular to each other. The front-to-back arrangement order of the first beam-splitting prism group 1 and the second beam-splitting prism group 2 along the optical path can be interchanged. After two stages of beam splitting, a two-dimensional beam array of M rows and N columns is formed. The diffraction grating array 3 is correspondingly set as a two-dimensional array containing M×N sub-grating units 33. The two-stage beam splitting directions are perpendicular, which can expand the one-dimensional array into a two-dimensional beam array of M rows and N columns to meet the requirements of scenarios such as area array optical interconnection and two-dimensional parallel detection. The two-dimensional sub-grating array is matched one-to-one with the two-dimensional beam array, and the power of each beam unit is independently modulated to realize arbitrary beam splitting ratio control and switching of the two-dimensional array.

[0028] In this embodiment, an incident polarization passivation device 4 is also provided on the incident side of the beam splitter prism group. The incident polarization passivation device 4 is used to control the polarization state of the incident beam; polarization normalization is completed at the incident end, so that the subsequent beam splitter works under stable polarization conditions, thereby improving the performance consistency and environmental adaptability of the entire device.

[0029] In this embodiment, the output side of the diffraction grating array 3 is also provided with an output polarization passivation device 5. The output polarization passivation device 5 is used to control the polarization state of the effective output beam. It can further filter high-order diffraction stray light through polarization characteristics, improve the signal-to-noise ratio of the effective 0th order beam, and optimize the output beam quality.

[0030] In this embodiment, the beam splitter 6 is a dielectric film or a metal film. The dielectric film achieves transmittance and reflectance control by alternately depositing multilayer thin films of high and low refractive index materials. The metal film achieves transmittance and reflectance control by adjusting the film thickness. The dielectric film is based on multi-beam interference beam splitting, with low absorption loss, high energy utilization, and high beam splitting ratio accuracy, making it suitable for low-loss scenarios. The metal film has a simple film structure, low processing cost, low sensitivity of beam splitting characteristics to polarization and wavelength, and a wide applicable spectral range.

[0031] In one embodiment of this invention, in the same beam-splitting prism group, the angles between each beam-splitting membrane 6 and the beam-splitting direction are equal, and the output sub-beams 81 are parallel to each other, forming a collimated beam array; when all beam-splitting membrane angles are consistent, the output sub-beams are all parallel, directly generating a collimated beam array without the need for additional collimating elements.

[0032] In another embodiment of this invention, in the same beam-splitting prism group, at least one beam-splitting film 6 has an angle different from the beam-splitting direction than the other beam-splitting films 6, and the output sub-beams 81 are non-parallel beams; by generating a non-parallel beam array with different tilt angles, each sub-beam points to a different spatial position, directly matching the distributed optoelectronic device without the need for additional deflection elements.

[0033] As one embodiment of the diffraction grating array 3, such as Figure 3-4 As shown, the diffraction grating array 3 includes N rows of first beam-splitting regions 31 and M rows of second beam-splitting regions 32. The first beam-splitting regions 31 extend along a first direction x, and the second beam-splitting regions 32 extend along a second direction y. The first beam-splitting regions 31 and the second beam-splitting regions 32 are intersected to form sub-grating units 33. Two-dimensional sub-grating units are generated by the intersection of two sets of orthogonal strip regions, which reduces the design and fabrication difficulty of the grating array. The diffraction characteristics in the two directions can be designed independently to optimize the 0th order transmission modulation accuracy.

[0034] Furthermore, the sub-grating unit 33 is either a surface-embossed grating or an embedded volume grating. The zero-order transmittance of each sub-grating unit 33 can be independently set by adjusting the grating phase modulation depth, scribe line depth, or grating period. Surface-embossed gratings are technologically mature, can be mass-produced, and are low-cost. Embedded volume gratings are located inside the material, have a smooth surface, are resistant to contamination, and have a long lifespan. The zero-order transmittance can be precisely controlled by adjusting parameters such as phase depth and scribe line depth, resulting in high modulation accuracy.

[0035] The technical solution of the embodiments of the present invention is based on a hybrid architecture of beam splitting and direction control by a reflecting prism and amplitude modulation switching by a diffraction grating. It combines the advantages of two devices with different optical principles to achieve high-degree-of-freedom beam array generation and control. The specific working principle is as follows: 1. Working principle of beam splitting by a reflecting prism: The prism beam splitter stage is a step-by-step beam splitting process using multiple layers of semi-transparent and semi-reflective beam splitting films. It utilizes the laws of light reflection and transmission to simultaneously achieve power distribution and pointing control.

[0036] (1) Power distribution principle: After the incident beam 8 is incident along the optical axis, it passes through each beam-splitting film in sequence, and is split into transmitted light and reflected light at each layer: The first beam passes directly through the first beam splitter and exits with a power equal to the total incident power multiplied by the transmittance of the first beam splitter.

[0037] The i-th sub-beam is first reflected by the first beam-splitting layer and propagates into the prism, passing sequentially through the second to (i-1)-th beam-splitting layers. Each layer results in a corresponding energy loss, and the beam is finally reflected out by the i-th beam-splitting layer. By pre-designing the transmittance and reflectance of each beam-splitting layer, the output power of each sub-beam can be precisely controlled. For example, to achieve equal-power beam splitting, the reflectance of each beam-splitting layer can be adjusted according to the number of layers the beam passes through, ensuring that the power of each reflected beam is consistent.

[0038] (2) Beam pointing control principle: The propagation direction of the emitted beam follows the law of reflection of light and is determined by the tilt angle of the beam splitter: the angle between the emitted beams of two adjacent sub-beams is equal to twice the angle difference of the corresponding beam splitter.

[0039] When all the beam splitters are tilted at the same angle, all the sub-beams deflect at the same angle and are parallel to each other after exiting, forming a collimated beam array.

[0040] When each beam splitter is set with a different tilt angle, each sub-beam deflects at a different angle, forming a non-parallel array with different included angles, which can point to different spatial positions.

[0041] When using a two-stage orthogonal prism array, the first stage controls the beam splitting and pointing in one direction, and the second stage controls the beam splitting and pointing in the vertical direction. The parameters of the two directions are designed independently and do not interfere with each other, ultimately forming a two-dimensional beam array.

[0042] 2. Working principle of diffraction grating amplitude modulation: The diffraction grating array is located on the output side of the prism beam splitter stage. Its function is to perform independent power attenuation on each sub-beam, so as to achieve fine control and rapid switching of the beam splitting ratio. The principle is based on the diffraction characteristics of the grating.

[0043] After the sub-beam is incident on the corresponding sub-grating unit, the periodic micro / nano structure of the grating modulates the phase or amplitude of the incident light, causing the beam to diffract and be divided into 0th-order transmitted light and higher-order diffracted light. The 0th-order transmitted light propagates in the same direction as the incident light and is the effective output beam; the higher-order diffracted light propagates outward at different angles, gradually moving away from the effective array as the propagation distance increases, and is eventually absorbed by the system aperture or the housing, which is an ineffective output.

[0044] The 0th-order transmittance of the sub-gratings is determined by the grating structural parameters: the phase grating controls the phase modulation depth by adjusting the scribe line depth and refractive index modulation amplitude, thereby regulating the 0th-order diffraction efficiency; the amplitude grating controls the 0th-order transmittance ratio by adjusting the duty cycle and material absorptivity. The parameters of each sub-grating can be designed independently, allowing for different attenuation ratios to be set for each sub-beam, thus enabling secondary modulation of the prism's base beam splitting ratio. By changing the grating array with different parameters, the overall beam splitting ratio can be quickly switched without re-fabricating the prism body.

[0045] The present 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 only for explaining the present invention and are not intended to limit the present invention, but rather to illustrate the specific structure of each component: The first beam-splitting prism group 1 includes N prism units 11 bonded side-by-side along the first direction x. The bonding surfaces of adjacent prism units 11 are coated with beam-splitting films 6, with a total of N-1 layers of beam-splitting films 6. The prism units 11 are made of fused silica glass, but other silicate optical glasses may also be used.

[0046] The beam splitter 6 employs a dielectric film system, consisting of alternating layers of high-refractive-index TiO2 and low-refractive-index SiO2. The optical thickness of each layer is 1 / 4 of the working wavelength. By adjusting the number of layers and the film system structure, the transmittance and reflectance of each layer of the beam splitter 6 can be precisely controlled. In another embodiment, the beam splitter 6 can also be a metal film made of metallic materials such as chromium or aluminum, with the transmittance / reflectance ratio adjusted by controlling the film thickness.

[0047] The angle between each beam splitter 6 and the first direction x can be set independently: when the angles of all beam splitters 6 are equal, the output is an array of parallel sub-beams 81 arranged along the x direction; when the angles of each beam splitter 6 are different, the output is an array of non-parallel sub-beams 81 with different exit angles.

[0048] The second beam splitter prism group 2 has the same structure as the first beam splitter prism group 1, including M prism units glued side by side along the second direction y, and a total of M-1 layers of row splitting films, which split each x-direction sub-beam again along the y direction, finally forming a two-dimensional beam array of M rows and N columns.

[0049] The diffraction grating array 3 is positioned on the exit side of the second beam-splitting prism group 2, and its substrate is fused silica glass. For example... Figure 3 , Figure 4 As shown, the diffraction grating array 3 includes N first beam-splitting regions 31 extending along the first direction x and M second beam-splitting regions 32 extending along the second direction y. The two beam-splitting regions are interleaved to form M×N independent sub-grating units 33. The position of each sub-grating unit 33 corresponds one-to-one with the two-dimensional beam array, and its effective size is larger than the diameter of the incident sub-beam spot, ensuring that the beam is completely incident and no crosstalk occurs.

[0050] In this embodiment, the sub-grating unit 33 is a buried phase grating fabricated by femtosecond laser direct writing, with a grating line spacing of 0.5~200μm and a grating structure thickness of 1~100μm, and the lines are located inside the glass substrate. By adjusting the laser processing parameters to change the phase modulation depth, the zero-order transmittance of each sub-grating unit 33 can be independently controlled. In other embodiments, the sub-grating unit 33 can also be a surface relief grating, fabricated by photolithography and nanoimprint lithography.

[0051] The diffraction grating array 3 and the second beam splitter prism group 2 adopt a detachable installation structure with precision slots and optical clamps, which facilitates quick replacement of grating arrays with different parameters and realizes beam splitting ratio switching.

[0052] The incident polarization passivation device 4 is disposed at the incident end of the first beam-splitting prism group 1. In this embodiment, a linear grating polarizer is used to convert the incident beam 8 into linearly polarized light in a specific direction, ensuring the stability of the transmission-to-reflection ratio of the beam-splitting film 6. The exit polarization passivation device 5 is disposed at the exit end of the diffraction grating array 3. In this embodiment, a quarter-wave plate is used to convert the linearly polarized light into circularly polarized light, adapting to the polarization requirements of the downstream system. In other embodiments, devices such as half-wave plates and polarizing beam-splitting prisms can also be used to achieve different polarization control functions.

[0053] As for the processing methods of each component: (1) Fabrication method of beam splitter prism assembly: The first beam-splitting prism group 1 and the second beam-splitting prism group 2 are manufactured using standard optical cold processing technology, as follows: Material cutting: The fused quartz blank is cut into long strips of base material. The length of the base material corresponds to the total length of multiple bundled prism units, and the cross-sectional size corresponds to the cross-section of a single prism unit.

[0054] Rough grinding and fine grinding: Rough grinding and fine grinding are performed on each optical surface of the long strip of substrate to control the flatness and angular tolerance of each surface and ensure that the tilt angle of the beam splitter film meets the design requirements.

[0055] Vacuum coating: Vacuum coating is performed on the finely ground beam splitting film surface, alternating high and low refractive index dielectric films or metal beam splitting films, and the film thickness is precisely controlled so that the transmittance and reflectance ratio of each beam splitting film reaches the design value.

[0056] Deepening the photoresist: Multiple coated elongated prism substrates are bonded together with photoresist according to the required angles to form an overall elongated prism array.

[0057] Cutting and shaping: The glued strip of parent material is cut along the direction perpendicular to its length to obtain multiple beam splitting prisms of uniform thickness. Each finished product is a complete one-dimensional beam splitting prism array.

[0058] The process of first making long strips and then cutting them into pieces allows a single base material to be cut into more than 5 bundle units, and a single coating can process more than 20 base materials. This results in high efficiency in mass production, and the products in the same batch have good consistency in optical performance and strong interchangeability.

[0059] (2) Fabrication method of diffraction grating array: This embodiment uses a femtosecond laser direct writing process, and the procedure is as follows: Substrate preparation: The fused silica glass substrate is cut to the target size, and the incident and exit surfaces are optically polished to ensure surface smoothness.

[0060] Direct-write processing: The glass substrate is placed on a femtosecond laser processing platform, with the laser focus concentrated inside the substrate. Line-by-line scanning and direct writing are performed according to design parameters. After processing the first sub-grating unit 33, the laser focus jumps to the starting position of the next unit, repeating the process until all M×N sub-grating units 33 are completed. During processing, the refractive index modulation depth of the grating is controlled by adjusting parameters such as laser power, scanning speed, and objective lens numerical aperture, thereby controlling the 0th order transmittance of each sub-grating unit 33. In mass production scenarios, surface relief gratings can also be fabricated using ultraviolet lithography and reactive ion etching, or mass replication can be achieved using nanoimprint lithography, further reducing costs.

[0061] (3) Component assembly method: The assembly method for each component can be selected according to requirements: Integrated high-stability scenario: Deep-bonded optical adhesive or ultraviolet optical adhesive is used to bond and fix the components, reducing interface reflection loss and improving structural strength.

[0062] For scenarios requiring grating replacement: the prism assembly is glued together as one unit, and the diffraction grating array 3 can be detached and installed using precision mechanical clamps and positioning slots to ensure accurate replacement alignment.

[0063] All components can also be installed separately in the same optical base or housing, with mechanical structure ensuring optical axis alignment, facilitating independent replacement and maintenance.

[0064] This embodiment also provides a beam array splitting method, which uses the above-mentioned reflection-diffraction hybrid beam array splitter. Taking an incident laser with a working wavelength of 1550nm and a total power of 100mW as an example, a 4×4 two-dimensional beam array is generated. The specific implementation steps are as follows: S1, Prism Beam Splitting: The incident beam 8 is incident along the z-axis to the first beam splitting prism group 1, first completing one-dimensional beam splitting in the x-direction, and then completing orthogonal beam splitting in the y-direction through the second beam splitting prism group 2.

[0065] The first beam-splitting prism group 1 comprises 4 prism units 11 and 4 layers of beam-splitting membranes 6. The angles between each beam-splitting membrane 6 and the x-axis are set to θ1=θ2=θ3=θ4=22.5°. The angles are determined according to the formula for the angle between adjacent beams φ. i-1 =2(θ i -θ i-1 Each sub-beam 81 exits at an angle of 0 and exits in a parallel, collimated manner along the z-axis.

[0066] To achieve equal-power beam splitting in four channels, the transmittance-to-reflection ratio of each beam splitter is calculated using the power formula: P1 = P in ×T1=25mW, therefore T1=25%, R1=75%; P2=P in ×R1×R2=25mW, therefore R2≈33.3%, T2≈66.7%; P3=P in ×R1×T2×R3=25mW, therefore R3=50%, T3=50%; P4=P in ×R1×T2×T3×R4=25mW, so R4=100%.

[0067] The structural parameters of the second beam splitter prism group 2 are consistent with those of the column beam splitter. It performs 4-way equal power beam splitting again along the y-direction, and finally outputs a 4×4 two-dimensional collimated beam array, with an initial power of 6.25mW for each sub-beam.

[0068] S2, Diffraction Amplitude Modulation: A 4×4 beam array corresponds one-to-one with the 16 sub-grating units 33 incident on the diffraction grating array 3.

[0069] In this embodiment, the sub-grating unit 33 is configured with a 0th order transmittance according to the row gradient, and the transmittance of the four rows is 40%, 60%, 80%, and 100% respectively. The sub-grating unit 33 diffracts part of the beam energy to higher diffraction orders and deviates from the effective optical path with the propagation distance, retaining only the 0th order transmitted light as the effective output. Finally, the effective beam power of the four rows is 2.5mW, 3.75mW, 5mW, and 6.25mW respectively, forming an output array with a power gradient distribution.

[0070] S3. Beam splitting ratio switching: When it is necessary to switch to full array equal power output, there is no need to modify the first beam splitter prism group 1 and the second beam splitter prism group 2. Only the current diffraction grating array 3 is removed and replaced with a grating array in which the 0th order transmittance of all sub-grating units 33 is 80%, so as to obtain 16 equal power beam arrays with a power of 5mW, and complete the rapid switching of beam splitting ratio.

[0071] like Figure 6-7 As shown, the beam output after processing by the sub-grating unit 33 will simultaneously contain a main beam array 71 with an unchanged propagation direction and a secondary beam array 72 with a changed propagation direction of a higher-order diffraction order. The main beam array 71 is the effective output, while the remaining arrays are ineffective outputs and gradually move away from the main beam array 71 as the propagation distance increases. The beam angle between the main beam arrays 71 is consistent with the beam array directly output by the reflection beam splitting order. The diagram shows the light field on two planes, the first plane A and the second plane B. In the first plane A, which is closer to the grating array 3, the secondary beams 72 and the main beams 71 are not completely separated. As the optical path increases and the beam reaches the second plane B, which is slightly farther away, the secondary beams 72 separate from the main beams 71, while the main beam array 71 is retained.

[0072] It should be noted that all directional indications (such as up, down, left, right, front, back, etc.) in the embodiments of the present invention are only used to explain the relative positional relationship and movement of each component in a certain specific posture (as shown in the figure). If the specific posture changes, the directional indication will also change accordingly.

[0073] Furthermore, in this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly and specifically defined.

[0074] In this invention, unless otherwise explicitly specified and limited, the terms "connection," "fixed," etc., should be interpreted broadly. For example, "fixed" can mean a fixed connection, a detachable connection, or an integral part; it can mean a mechanical connection or an electrical connection; it can mean a direct connection or an indirect connection through an intermediate medium; it can mean the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0075] Furthermore, the technical solutions of the various embodiments of the present invention can be combined with each other, but only if they are feasible for those skilled in the art. If the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

Claims

1. A reflection-diffraction hybrid beam splitter for a beam array, characterized in that, Along the optical path propagation direction, it includes at least one beam splitter prism group and a diffraction grating array (3). The beam splitter prism group includes several prism units (11) glued together side by side along the beam splitting direction. The glued surfaces of two adjacent prism units (11) are coated with beam splitting films (6). The transmittance and reflectance of each beam splitting film (6) are set independently, and the angle between each beam splitting film (6) and the beam splitting direction is set independently. After the incident beam (8) is transmitted and reflected sequentially through each beam splitting membrane, it forms a multi-path sub-beam (81) arranged along the beam splitting direction. The diffraction grating array (3) includes multiple sub-grating units (33) that correspond one-to-one with each sub-beam (81). Each sub-beam is independently incident on a sub-grating unit (33). The sub-grating unit (33) is used to diffract part of the energy of the incident sub-beam (81) to higher diffraction orders, retaining the 0th order transmitted light as the effective output beam. The final power of the corresponding effective output beam is independently modulated by the 0th order transmittance of each sub-grating unit (33). The diffraction grating array (3) is a replaceable structure. By replacing the diffraction grating array (3) with different 0th order transmittance distributions, the overall beam splitting ratio of the output beam array is switched.

2. The reflection-diffraction hybrid beam splitter according to claim 1, characterized in that, The beam splitter prism group includes a first beam splitter prism group (1) and a second beam splitter prism group (2) arranged sequentially along the optical path. The beam splitting direction of the first beam splitter prism group (1) is the first direction (x), and the beam splitting direction of the second beam splitter prism group (2) is the second direction (y). The first direction (x) and the second direction (y) are perpendicular to each other. The order of the first beam splitter prism group (1) and the second beam splitter prism group (2) along the optical path can be interchanged. After two-stage beam splitting, a two-dimensional beam array of M rows and N columns is formed. The diffraction grating array (3) is correspondingly set as a two-dimensional array containing M×N sub-grating units (33).

3. The reflection-diffraction hybrid beam splitter according to claim 1, characterized in that, The incident side of the beam splitter prism group is also provided with an incident polarization passivation device (4), which is used to control the polarization state of the incident beam.

4. The reflection-diffraction hybrid beam splitter according to claim 1, characterized in that, The output side of the diffraction grating array (3) is also provided with an output polarization passivation device (5), which is used to control the polarization state of the effective output beam.

5. The reflection-diffraction hybrid beam splitter according to claim 1, characterized in that, The beam splitter (6) is a dielectric film or a metal film. The dielectric film achieves the control of transmittance and reflectance by alternately depositing multilayer thin films of high and low refractive index materials. The metal film achieves the control of transmittance and reflectance by adjusting the film thickness.

6. The reflection-diffraction hybrid beam splitter according to claim 1, characterized in that, In the same beam splitter prism group, the angle between each beam splitter (6) and the beam splitting direction is equal, and the output sub-beams (81) are parallel to each other, forming a collimated beam array.

7. The reflection-diffraction hybrid beam splitter according to claim 1, characterized in that, In the same beam splitter prism group, at least one beam splitter (6) has an angle with the beam splitting direction that is different from the other beam splitter (6), and the output sub-beams (81) are non-parallel beams.

8. The reflection-diffraction hybrid beam splitter according to claim 2, characterized in that, The diffraction grating array (3) includes N rows of first beam-splitting regions (31) and M rows of second beam-splitting regions (32). The first beam-splitting regions (31) extend along a first direction (x), and the second beam-splitting regions (32) extend along a second direction (y). The first beam-splitting regions (31) and the second beam-splitting regions (32) are intersected to form sub-grating units (33).

9. The reflection-diffraction hybrid beam splitter according to claim 8, characterized in that, The sub-grating unit (33) is a surface relief grating or a buried volume grating. The 0th order transmittance of each sub-grating unit (33) is set independently by adjusting the grating phase modulation depth, scribe line depth or grating period.

10. A beam array splitting method, employing a reflection-diffraction hybrid beam array splitter as described in any one of claims 1-9, characterized in that, Includes the following steps: S1, prism beam splitting: the incident beam is incident on the beam splitting prism group, and after successive transmission and reflection through multiple layers of beam splitting film, it is split into multiple sub-beams arranged along the beam splitting direction (81). Among them, the first sub-beam is the transmitted light that passes through the first beam-splitting film, and the output power satisfies: ; In the formula, The total power of the incident beam. The transmittance of the first beam splitter layer; The i-th sub-beam is a beam that, after being reflected by the first beam-splitting layer, passes sequentially through the second to (i-1)-th beam-splitting layers, and is then reflected by the i-th beam-splitting layer before exiting. The exit power satisfies the following: ； In the formula, The reflectivity of the first beam-splitting film. The transmittance of the beam splitters are, in order, from the 2nd to the (i-1th)th layers. Let be the reflectivity of the i-th beam splitter layer; The initial power of each sub-beam is independently allocated by presetting the transmittance and reflectance of each beam splitter; the exit angle between two adjacent sub-beams satisfies: ； In the formula, Let be the angle between the i-th beam-splitting layer and the beam-splitting direction. The angle between the (i-1)th beam splitter and the beam splitting direction is used to independently control the angle between the output direction of each sub-beam and the adjacent sub-beam by presetting the tilt angle of each beam splitter. S2, Diffraction Amplitude Modulation: Each sub-beam (81) after splitting is incident on a corresponding sub-grating unit (33). The diffraction effect of the sub-grating unit (33) is used to deflect part of the beam energy to higher diffraction orders, retaining only the 0th order transmitted light as the effective output. The final power of the corresponding effective beam is modulated by the 0th order transmittance of each sub-grating unit. S3, beam splitting ratio switching: Replace the diffraction grating array (3) with different 0th order transmittance distributions, and adjust the overall beam splitting ratio of the output beam array without changing the beam splitting prism group.

Images