A holographic planar diffraction grating

Abstract

The utility model discloses a holographic plane diffraction grating concretely relates to grating field, including photosensitive base, the recessed holographic information groove is seted up on photosensitive base upper surface, has high bright grating structure in the holographic information groove, and high bright grating structure is the regular arrangement micro - nanometer structure, and the transparent holographic base is bonded to the holographic information groove top, and the transparent holographic base upper surface is flush with photosensitive base upper surface, and the transparent holographic base lower surface sets up the auxiliary grating structure of periodic arrangement. The utility model discloses with the synergies of auxiliary grating and high bright grating promote the precision of spectrometer and adapt to the multi - wavelength range, and the molten silicon piece base enhances structural stability to cope with environmental change, and the positioning structure is convenient and the accurate assembly of optical equipment, and rely on mature etching process and parameter quantization easy management and control, and the whole gives consideration to excellent diffraction performance, high practicality and batch production feasibility.

Description

Technical Field

[0001] This utility model relates to the field of gratings, and more specifically, to a holographic planar diffraction grating. Background Technology

[0002] Existing holographic planar diffraction gratings are widely used in optical spectroscopy, but they generally suffer from performance and practicality shortcomings: most adopt a single-layer grating structure, relying solely on a single diffraction unit to achieve spectral dispersion, lacking preprocessing of the incident light, resulting in limited spectral dispersion accuracy and difficulty in adapting to multiple wavelength ranges, failing to meet the requirements of high-precision optical equipment; some gratings use substrate materials with insufficient mechanical strength and optical stability, making them susceptible to deformation due to environmental factors such as temperature fluctuations and mechanical vibrations, which in turn interfere with the light propagation path and reduce diffraction stability; in addition, the core structural parameters in the manufacturing process of some gratings are not clearly controlled, relying on complex processing procedures, making it difficult to ensure performance consistency during mass production, thus restricting their widespread application in practical scenarios. Utility Model Content

[0003] To solve the above-mentioned technical problems, this utility model provides a holographic planar diffraction grating, including a photosensitive substrate. The upper surface of the photosensitive substrate has a recessed holographic information groove, and the holographic information groove has a high-brightness grating structure. The high-brightness grating structure is a regularly arranged micro-nano structure. A transparent holographic substrate is bonded to the top of the holographic information groove. The upper surface of the transparent holographic substrate is flush with the upper surface of the photosensitive substrate. The lower surface of the transparent holographic substrate has a periodically arranged auxiliary grating structure.

[0004] In a preferred embodiment, the substrate includes a photosensitive substrate with a recessed holographic information groove on its upper surface. The holographic information groove contains a high-brightness grating structure, which is a regularly arranged micro-nano structure. A transparent holographic substrate is bonded to the top of the holographic information groove. The upper surface of the transparent holographic substrate is flush with the upper surface of the photosensitive substrate. The lower surface of the transparent holographic substrate has a periodically arranged auxiliary grating structure.

[0005] In a preferred embodiment, the photosensitive substrate is a fused silicon wafer.

[0006] In a preferred embodiment, photoresist is laid at the bottom of the holographic information slot, with a thickness of 3-5 μm. The high-brightness grating structure is based on the photoresist, and textures are etched on the photoresist to form the high-brightness grating structure.

[0007] In a preferred embodiment, the high-brightness grating structure is continuously distributed on the working surface of the holographic information slot, and the coverage area is not less than 80% of the bottom area of ​​the holographic information slot.

[0008] In a preferred embodiment, the texture is a regularly distributed reflective surface with a depth of 1-2 μm and the reflective surface is square.

[0009] In a preferred embodiment, the auxiliary grating structure includes a plurality of parallel rectangular micro-nano units and triangular micro-nano units. Both the rectangular and triangular micro-nano units are grooves formed on the lower surface of the transparent holographic substrate. The rectangular and triangular micro-nano units are arranged alternately and parallel to each other.

[0010] In a preferred embodiment, a gap is left between the two ends of the rectangular micro / nano unit and the two sides of the transparent holographic substrate, and the two ends of the rectangular micro / nano unit extend to the two sides of the transparent holographic substrate.

[0011] In a preferred embodiment, the triangular micro / nano unit has an isosceles triangle cross-section with a vertex angle of 30-60° and a height of 0.1-1μm, and the rectangular micro / nano unit has a rectangular cross-section with a groove width of 0.2-2μm and a groove depth of 0.1-0.8μm.

[0012] The technical effects and advantages of this utility model are as follows:

[0013] This invention improves the spectral accuracy and adapts to multiple wavelength ranges by leveraging the synergistic effect of auxiliary gratings and high-brightness gratings. The molten silicon substrate enhances structural stability to cope with environmental changes. The positioning structure facilitates precise assembly with optical equipment. It relies on mature etching technology and has easily quantifiable and controllable parameters. Overall, it balances excellent diffraction performance, high practicality, and feasibility for mass production. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the overall structure of this utility model;

[0015] Figure 2 This is a schematic diagram of the internal part of the holographic information slot of this utility model;

[0016] Figure 3 This is a schematic diagram of the lower surface of the transparent holographic substrate of this utility model;

[0017] Figure 4 This is a schematic diagram of the internal structure of this utility model.

[0018] Explanation of reference numerals in the attached figures: 1 Photosensitive substrate, 2 Holographic information groove, 3 High-brightness grating structure, 4 Transparent holographic substrate, 5 Auxiliary grating structure, 6 Positioning hole, 7 Positioning step, 8 Photoresist, 9 Rectangular micro / nano unit, 10 Triangular micro / nano unit, 11 Mounting base. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments. The embodiments of the present invention are given for illustrative and descriptive purposes only, and are not intended to be exhaustive or to limit the present invention to the disclosed forms. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described to better illustrate the principles and practical applications of the present invention, and to enable those skilled in the art to understand the present invention and design various embodiments with various modifications suitable for a particular purpose.

[0020] like Figure 1-4 The holographic planar diffraction grating shown includes a photosensitive substrate 1, which is a fused silicon wafer. A recessed holographic information groove 2 is formed on the upper surface of the photosensitive substrate 1. A high-brightness grating structure 3 is formed in the holographic information groove 2. The high-brightness grating structure 3 is a regularly arranged micro-nano structure. A transparent holographic substrate 4 is bonded to the top of the holographic information groove 2. The upper surface of the transparent holographic substrate 4 is flush with the upper surface of the photosensitive substrate 1. A periodically arranged auxiliary grating structure 5 is formed on the lower surface of the transparent holographic substrate 4.

[0021] Based on the above, the photosensitive substrate 1 is made of fused silicon wafer, which has high mechanical strength, excellent heat resistance and optical stability, and can prevent the grating from deforming due to temperature fluctuations and mechanical vibrations during long-term use, thus ensuring the stability of the light propagation path; the holographic information groove 2 recessed on the upper surface of the photosensitive substrate 1 provides a dedicated space for the high-brightness grating structure 3, limits the core diffraction area, and prevents the high-brightness grating structure 3 from being exposed to external wear.

[0022] The transparent holographic substrate 4 has good light transmittance, allowing incident light to pass smoothly through to the high-brightness grating structure 3 below. On the other hand, it is flush with the upper surface of the photosensitive substrate 1 and firmly bonded, forming a compact integrated structure, reducing light reflection interference between multi-layer structures. At the same time, the auxiliary grating structure 5 on the lower surface of the transparent holographic substrate 4 can perform preliminary dispersion and phase modulation on the incident light. By utilizing the refraction difference of different wavelengths of light by the periodic grooves, it lays the foundation for the accurate spectral dispersion of the subsequent high-brightness grating structure 3, avoiding the problem of insufficient spectral dispersion accuracy caused by the incident light directly entering the core diffraction stage.

[0023] A plurality of positioning holes 6 are provided at the edge of the upper surface of the photosensitive substrate 1, and a mounting base 11 is provided on the lower surface of the photosensitive substrate 1. A recessed positioning step 7 is provided between the mounting base 11 and the photosensitive substrate 1.

[0024] Based on the above, the positioning hole 6 on the edge of the photosensitive substrate 1 can precisely cooperate with the positioning post of the external optical equipment to fix the grating's lateral position, avoiding misalignment of the incident light and the grating diffraction area caused by lateral displacement during assembly; the mounting base 11 on the lower surface of the photosensitive substrate 1 provides stable support for the grating, while the recessed positioning step 7 between the mounting base 11 and the photosensitive substrate 1 can achieve precise alignment of their longitudinal positions, ensuring that the mounting base 11 and the photosensitive substrate 1 fit tightly without gaps or shaking, further ensuring the overall installation accuracy of the grating in the optical system; the synergistic effect of the positioning hole 6 and the positioning step 7 can effectively eliminate the influence of assembly deviation on the light diffraction path, avoid unstable beam splitting effect caused by grating position displacement, and ensure that the diffraction accuracy always meets the usage requirements.

[0025] The bottom of the holographic information slot 2 is covered with photoresist 8, which has a thickness of 3-5 μm. The high-brightness grating structure 3 is based on the photoresist 8, and textures are etched on the photoresist 8 to form the high-brightness grating structure 3. The high-brightness grating structure 3 is continuously distributed on the working surface of the holographic information slot 2, and the coverage area is not less than 80% of the bottom area of ​​the holographic information slot 2. The texture is a regularly distributed reflective mirror surface with a depth of 1-2 μm and a square reflective mirror surface.

[0026] Based on the above, the 3-5µm thick photoresist 8 laid at the bottom of the holographic information slot 2 serves as the etching substrate for the high-brightness grating structure 3. Its thickness ensures that the reflective mirror formed by subsequent etching has sufficient structural strength, while avoiding the reflective mirror being easily damaged due to excessive thinness or affecting the light reflection efficiency due to excessive thickness. A square reflective mirror is etched based on the photoresist 8, and periodic micro-nano units are formed by utilizing the regularity of the square structure. When the incident light, which has been pre-processed by the auxiliary grating, reaches the reflective mirror, light of different wavelengths will undergo specific diffraction interference under the action of the periodic reflective mirror. Light with similar wavelengths diffracts in the same direction, while light with large wavelength differences is separated in different directions, thereby realizing the core function of decomposing polychromatic light into monochromatic light according to wavelength.

[0027] The high-brightness grating structure 3 covers an area of ​​no less than 80% of the working surface of the holographic information slot 2, which can ensure sufficient effective diffraction area, reduce stray light generation caused by insufficient diffraction area, and improve the reception efficiency and signal-to-noise ratio of optical signal, ensuring the clarity and stability of the beam splitting effect.

[0028] The auxiliary grating structure 5 includes several parallel rectangular micro / nano units 9 and triangular micro / nano units. Both the rectangular micro / nano units 9 and triangular micro / nano units are grooves formed on the lower surface of the transparent holographic substrate 4. The rectangular micro / nano units 9 and triangular micro / nano units 10 are arranged alternately and parallel to each other. There is a gap between the two ends of the rectangular micro / nano unit 9 and the two sides of the transparent holographic substrate 4. The two ends of the rectangular micro / nano unit extend to the two sides of the transparent holographic substrate 4. The triangular micro / nano unit 10 has an isosceles triangle cross-section with a vertex angle of 30-60° and a height of 0.1-1μm. The rectangular micro / nano unit 9 has a rectangular cross-section with a groove width of 0.2-2μm and a groove depth of 0.1-0.8μm.

[0029] Based on the above, the auxiliary grating structure 5 adopts a design of rectangular micro-nano units 9 and triangular micro-nano units 10 arranged in parallel at intervals. The two groove structures have different refraction angles for incident light. The rectangular groove has a better refraction modulation effect for medium and long wavelength light, while the triangular groove has a more accurate refraction modulation effect for short wavelength light. The two can work together to cover a wider wavelength range, solving the problem of insufficient adaptability of traditional single-structure auxiliary gratings to specific wavelength bands.

[0030] Among them, the rectangular micro-nano unit 9 has gaps at both ends and the edge of the transparent holographic substrate 4, which can avoid the processing error of the substrate edge from affecting the periodicity of the rectangular unit and ensure its uniformity of light modulation; the triangular micro-nano unit 10 extends to the edge of the substrate at both ends, which can maximize its coverage of incident light and improve the preprocessing effect of short wavelength light.

[0031] Furthermore, when the incident light penetrates the transparent holographic substrate 4 and reaches the auxiliary grating, the two micro-nano units will perform preliminary dispersion according to the wavelength difference of the light, and the polychromatic light will be initially separated according to wavelength, reducing the spectral splitting pressure of the subsequent high-brightness grating structure 3, and further improving the overall spectral splitting accuracy.

[0032] Obviously, the described embodiments are only a part of the embodiments of this utility model, and not all of them. All other embodiments obtained by those skilled in the art and related fields based on the embodiments of this utility model without creative effort should fall within the protection scope of this utility model. Structures, devices, and operating methods not specifically described and explained in this utility model, unless otherwise specified or limited, shall be implemented according to conventional means in the art.

Claims

1. A holographic planar diffraction grating, characterized in that: The device includes a photosensitive substrate, on the upper surface of which a recessed holographic information groove is formed. The holographic information groove contains a high-brightness grating structure, which is a regularly arranged micro-nano structure. A transparent holographic substrate is bonded to the top of the holographic information groove. The upper surface of the transparent holographic substrate is flush with the upper surface of the photosensitive substrate. A periodically arranged auxiliary grating structure is formed on the lower surface of the transparent holographic substrate.

2. A holographic planar diffraction grating according to claim 1, characterized in that: Several positioning holes are provided at the edge of the upper surface of the photosensitive substrate, and a mounting base is provided on the lower surface of the photosensitive substrate. A recessed positioning step is provided between the mounting base and the photosensitive substrate.

3. A holographic planar diffraction grating according to claim 1, characterized in that: The photosensitive substrate is a fused silicon wafer.

4. A holographic planar diffraction grating according to claim 1, characterized in that: The bottom of the holographic information slot is covered with photoresist with a thickness of 3-5 μm. The high-brightness grating structure is based on the photoresist, and textures are etched on the photoresist to form the high-brightness grating structure.

5. A holographic planar diffraction grating according to claim 4, characterized in that: The high-brightness grating structure is continuously distributed on the working surface of the holographic information slot, and the coverage area is not less than 80% of the bottom area of ​​the holographic information slot.

6. A holographic planar diffraction grating according to claim 4, characterized in that: The texture is a regularly distributed reflective surface with a depth of 1-2 μm and the reflective surface is square.

7. A holographic planar diffraction grating according to claim 1, characterized in that: The auxiliary grating structure includes several parallel rectangular and triangular micro-nano units. Both the rectangular and triangular micro-nano units are grooves formed on the lower surface of the transparent holographic substrate. The rectangular and triangular micro-nano units are arranged alternately and parallel to each other.

8. A holographic planar diffraction grating according to claim 7, characterized in that: There is a gap between the two ends of the rectangular micro / nano unit and the two sides of the transparent holographic substrate, and the two ends of the rectangular micro / nano unit extend to the two sides of the transparent holographic substrate.

9. A holographic planar diffraction grating according to claim 7, characterized in that: The triangular micro / nano unit has an isosceles triangle cross-section with a vertex angle of 30-60° and a height of 0.1-1μm. The rectangular micro / nano unit has a rectangular cross-section with a groove width of 0.2-2μm and a groove depth of 0.1-0.8μm.

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