Wide-spectrum integrated spectrometer based on gradient photonic crystal dispersion
By designing an ordered arranged periodic gradient scattering hole array photonic crystal and CMOS detector in the spectrometer, using the ultra-prism effect and gradient period of the photonic crystal, high-precision spectral resolution in small volumes is achieved, and the spectrometer volume and no The problem of sequence structure is suitable for applications in different bands.
Patent Information
- Application Number
- CN202411456915.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-10-18
- Publication Date
- 2025-01-14
AI Technical Summary
The existing spectrometers are difficult to reduce in size while ensuring wavelength resolution, and the disordered structure of spectrometers based on hole scattering lacks design specifications and difficult processing. The ultra-prism effect bandwidth is narrow and requires optical path accumulation, which limits its application.
The photonic crystals of periodic gradient scattering hole array are designed in an orderly arranged manner, and the ultra-prism effect and gradient period of the photonic crystal are used to scatter and guide light at different wavelengths. The spectrum is reconstructed in combination with the CMOS detector to achieve high-precision spectral resolution within a compact volume.
The integrated spectrometer with high resolution and wide spectral range in small volumes overcomes the problems of volume limitations and difficulty in processing disordered structures of traditional spectrometers, reduces costs, and is suitable for applications in different bands.
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Figure CN119309673A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a wide spectrum integrated spectrometer based on gradient photonic crystal dispersion, belonging to the technical field of spectrum analysis. Background Art
[0002] Spectrometers based on dispersive elements such as gratings are a traditional integrated spectrometer design method, but since this type of spectrometer requires the accumulation of optical paths, it is difficult to further reduce the size while ensuring a certain wavelength resolution. Integrated spectrometers based on filtering obtain spectral information by detecting the light intensity output by different filter channels. In order to meet a wider spectral monitoring range, it is necessary to design enough filter structures. The spectral monitoring range is limited by the free spectral range of the resonant structure, so this type of method is difficult to expand to a wide spectrum. Spectrometers based on hole scattering do not need to guide monochromatic light to a single position, and the spatial distribution of wavelength information is aliased. Spectral resolution is achieved through computational reconstruction methods, which can have higher resolution in a smaller volume. However, they all use disordered structures, have no standard design specifications, and are difficult to repeat. This limits the practical application of this type of spectrometer.
[0003] Photonic crystals composed of periodically arranged scattering hole arrays have a super prism effect. When the angle of the incident light is close to a certain angle, a small change in the incident angle will lead to a significant change in the refraction angle. However, the excitation of the super prism effect of photonic crystals often requires complex structures for beam shaping. At the same time, the response bandwidth is narrow, generally only tens of nanometers, and a certain optical path accumulation is required to convert angular dispersion into spatial dispersion. These problems have prevented this effect from being applied to spectrometer design.
[0004] Therefore, technicians in this field need to overcome the problems of disordered structures in hole scattering spectrometers having no design specifications, difficult processing, and the super prism effect of ordered scattering hole photonic crystals requiring beam shaping, narrow bandwidth, and optical path accumulation. Summary of the invention
[0005] Objective: To overcome the deficiencies in the prior art, the present invention provides a wide spectrum integrated spectrometer based on gradient photonic crystal dispersion, designs an orderly arranged, periodically gradient scattering hole array, utilizes the super prism effect of photonic crystals and the gradient period to guide the scattering of light of different wavelengths, and realizes effective spatial dispersion in a compact volume.
[0006] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is:
[0007] A wide spectrum integrated spectrometer based on gradient photonic crystal dispersion comprises an optical chip and a CMOS detector.
[0008] Among them, the optical chip includes a beam splitter, an optical waveguide, and a gradient photonic crystal. The optical waveguide includes an input optical waveguide and an output optical waveguide. The input end of the beam splitter is connected to the input optical waveguide, and the multiple output ends of the beam splitter are respectively connected to one end of the output optical waveguide, and the other end of each output optical waveguide is respectively connected to the gradient photonic crystal.
[0009] The CMOS detector is used to reconstruct the spatial distribution of scattered light intensity leaked from the gradient photonic crystal to obtain an input spectrum.
[0010] As a preferred solution, the CMOS detector is placed at the bottom or side of the optical chip.
[0011] As a preferred solution, the beam splitter is used to split the incident light in the input optical waveguide into a plurality of split beams of different wavelengths, and couple the split beams of different wavelengths into corresponding output optical waveguides respectively.
[0012] As a preferred solution, the output optical waveguide is a single-mode optical waveguide, and the width of the single-mode optical waveguide is determined by the wavelength of the transmitted split beam light.
[0013] As a preferred solution, the gradient photonic crystal comprises a lattice, the lattice is distributed in an array, and a scattering hole array composed of scattering holes arranged in a 2x2 matrix is arranged on the lattice.
[0014] As a preferred solution, the period dx of the scattering hole array of the lattice along the waveguide extension direction multiplied by the effective refractive index of the output optical waveguide is 0.5 -0.7 , Indicates the wavelength of the split light in the output optical waveguide.
[0015] As a preferred embodiment, the period dx of the scattering hole array of the lattice in the gradient photonic crystal along the extension direction of the waveguide gradually increases from large to small, and the maximum value of the period dx of the scattering hole array along the extension direction of the waveguide is determined by the longest wavelength of the split light in the output optical waveguide, and the minimum value is determined by the shortest wavelength of the split light in the output optical waveguide.
[0016] As a preferred solution, the period dx of the scattering hole array along the waveguide extension direction is expressed as follows:
[0017]
[0018] in, represents the effective refractive index of the output optical waveguide, The wavelength of the split light in the output optical waveguide.
[0019] As a preferred solution, the ratio of the diameter D of the scattering holes of the lattice to the period dx of the scattering hole array along the waveguide extension direction is 0.6.
[0020] As a preferred solution, the ratio of the period dy of the scattering hole array of the lattice perpendicular to the waveguide extension direction to the period dx of the scattering hole array along the waveguide extension direction is 1.5.
[0021] Beneficial effects: The wide spectrum integrated spectrometer based on gradient photonic crystal dispersion provided by the present invention realizes high-precision spectral resolution in a very small volume by designing a chirped array of scattering holes on the side of the waveguide to form a photonic crystal, and utilizing the sensitive angular dispersion of the photonic crystal and the wavelength guidance of the gradient structure in space.
[0022] In order to further broaden the spectral response range, a beam splitter is used to couple the input light into different optical waveguides, and the photonic crystals on the side of each optical waveguide realize spatial dispersion of the light in the corresponding wavelength range. A CMOS detector is used to detect the scattered light intensity distribution on the side or bottom of the photonic crystal output light, and the spectrum is reconstructed using the light intensity distribution. The design of this integrated spectrometer overcomes the problem that the resolution accuracy of traditional spectrometers is limited by volume, and realizes an integrated spectrometer with high resolution and wide spectral range.
[0023] Furthermore, compared with traditional large-scale spectrometers, the present invention is smaller in size and lower in cost, and maintains a higher spectral resolution and a wider spectral response range.
[0024] Furthermore, compared with other integrated spectrometers, the present invention overcomes the problem of volume limiting spectral resolution and maintains higher performance indicators in a compact volume.
[0025] Furthermore, compared with the scattering-based integrated reconstruction spectrometer, the present invention overcomes the problem of disordered structures having no design specifications and is convenient for batch processing.
[0026] Furthermore, compared with other photonic crystal dispersion structures, the present invention utilizes waveguide side coupling and a periodic gradient structure to achieve large-angle dispersion and greatly reduce the required accumulated optical path.
[0027] Furthermore, by adjusting the number of waveguides and the structural parameters of the photonic crystal, the invention can be applied to various bands such as near-ultraviolet, visible light, and near-infrared to meet the application requirements of different occasions. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 It is a schematic diagram of the structure of the integrated spectrometer of the present invention.
[0029] Figure 2 Schematic diagram of the top view of the output optical waveguide and the gradient photonic crystal. DETAILED DESCRIPTION
[0030] The following is a clear and complete description of the technical solutions in the examples of the present invention in conjunction with the accompanying drawings in the examples of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative work are within the protection scope of the present invention.
[0031] The present invention will be further described below in conjunction with specific embodiments.
[0032] Embodiment 1:
[0033] This embodiment introduces a wide spectrum integrated spectrometer based on gradient photonic crystal dispersion, such as Figure 1 As shown, it includes an optical chip 1 and a CMOS detector 2.
[0034] Among them, the optical chip 1 includes a beam splitter 101, an optical waveguide, and a gradient photonic crystal 102. The optical waveguide includes an input optical waveguide 103 and an output optical waveguide 104. The input end of the beam splitter 101 is connected to the input optical waveguide 103, and the multiple output ends of the beam splitter 101 are respectively connected to one end of the output optical waveguide 104, and the other end of each output optical waveguide 104 is respectively connected to the gradient photonic crystal 102.
[0035] The CMOS detector 2 is placed at the bottom or side of the optical chip 1 .
[0036] The present invention can effectively stimulate the super prism effect by coupling the output optical waveguide 104 to the side of the gradient photonic crystal 102, so that the propagation angle of light inside the photonic crystal 102 changes rapidly with the wavelength, thereby achieving significant wavelength differentiation in a very small volume.
[0037] Secondly, multiple gradient photonic crystals 102 and output optical waveguides 104 are designed at the same time, and are connected in parallel using a beam splitter 101, thereby achieving a larger working bandwidth.
[0038] Furthermore, the beam splitter 101 is used to split the incident light in the input optical waveguide 103 into a plurality of split beams of different wavelengths, and couple the split beams of different wavelengths into corresponding output optical waveguides 104 , respectively.
[0039] Furthermore, the CMOS detector 2 is used to reconstruct the spatial distribution of scattered light intensity leaking from the bottom or side of the gradient photonic crystal 102 to obtain an input spectrum.
[0040] Furthermore, the number of beam splittings performed by the beam splitter 101 is determined by the bandwidth of the spectrometer detection wavelength.
[0041] Furthermore, the output optical waveguide 104 is a single-mode optical waveguide, and the width of the single-mode optical waveguide is determined by the wavelength of the transmitted split beam light.
[0042] Furthermore, the gradient photonic crystal 102 is disposed on one side of the output optical waveguide 104 , and the energy of the split light is coupled into the gradient photonic crystal 102 when propagating in the output optical waveguide 104 .
[0043] Further, such as Figure 2 As shown, the gradient photonic crystal 102 includes a lattice 1021, and the lattice 1021 is distributed in an array.
[0044] Furthermore, the lattice 1021 is provided with a scattering hole array consisting of scattering holes 1022 arranged in a 2x2 matrix.
[0045] Furthermore, the period dx of the scattering hole array of the lattice 1021 along the waveguide extension direction multiplied by the effective refractive index of the output optical waveguide 104 is 0.5. -0.7 In the range (preferably 0.6 ), It represents the wavelength of the split light in the output optical waveguide 104 and has a significant dispersion effect.
[0046] Furthermore, the period dx of the scattering hole array of the lattice 1021 in the gradient photonic crystal 102 along the waveguide extension direction gradually increases from large to small, and the maximum value of the period dx of the scattering hole array along the waveguide extension direction is determined by the longest wavelength of the split light in the output optical waveguide 104, and the minimum value is determined by the shortest wavelength of the split light in the output optical waveguide 104, which has a significant dispersion effect.
[0047] Furthermore, the period dx of the scattering hole array along the waveguide extension direction is expressed as follows:
[0048]
[0049] in, represents the effective refractive index of the output optical waveguide 104, The wavelength of the split light in the output optical waveguide 104.
[0050] Furthermore, the ratio of the diameter D of the scattering holes 1022 of the lattice 1021 to the period dx of the scattering hole array along the waveguide extension direction is 0.6.
[0051] Furthermore, the ratio of the period dy of the scattering hole array of the lattice 1021 perpendicular to the waveguide extension direction to the period dx of the scattering hole array along the waveguide extension direction is 1.5.
[0052] Furthermore, the optical chip 1 further comprises a base layer 105 , a beam splitter 101 , an optical waveguide, and a gradient photonic crystal 102 are arranged on the top surface of the base layer 105 , and the material of the base layer is silicon dioxide.
[0053] Embodiment 2:
[0054] For different target wavelength ranges of the integrated spectrometer, the wavelength range from near-ultraviolet, visible light to near-infrared can be covered by modifying the optical waveguide width, the number of beam splitters and the period size of the scattering array in the gradient photonic crystal.
[0055] An embodiment of a gradient photonic crystal:
[0056] The gradient photonic crystal uses a silicon dioxide substrate and a silicon nitride optical waveguide. The incident light is polarized in the quasi-TE mode in the optical waveguide, that is, the electric field polarization direction is parallel to the material interface. The wave vector of the optical waveguide along the propagation direction should maintain a certain ratio with the lattice of the gradient photonic crystal to stimulate the super prism effect of the photonic crystal and achieve strong spatial dispersion capability, that is, Depending on the design parameters, the product of the period dx in the waveguide extension direction and the effective refractive index of the waveguide is maintained at approximately 0.5 -0.7 between.
[0057] According to the above-mentioned proportional parameters, the present invention can provide a design scheme, by changing the width of the single-mode waveguide to maintain the effective refractive index of the waveguide at about 1.58, that is, when the designed wavelength response range is , then the period range of the lattice in the waveguide extension direction should be In addition, the lattice size of the photonic crystal composed of the scattering hole array perpendicular to the waveguide extension direction is about 1.5 times the maximum lattice size along the waveguide extension direction, that is, , remains unchanged in the same group of scattering hole arrays. The diameter of the scattering hole is about 0.6 times the maximum lattice along the waveguide extension direction, that is, , remains unchanged within the same set of scattering hole arrays.
[0058] The final designed structure can achieve a spatial dispersion capability of 1μm / n𝑚 in only 3 microns of space within the wavelength range of 400nm-800nm. The first-order diffraction dispersion capability of a traditional 500nm period grating is about 0.10° / nm, and a 500μm optical path is required to achieve the same effect. The structure of the present invention has more than 100 times the performance of a traditional periodic grating. The size of a single scattering hole array is within 0.01mm×0.05mm, and eight scattering hole arrays can cover the wavelength range of 400nm-800nm, and are connected in parallel with a beam splitter. The overall size of the final optical chip is within 0.5mm×0.3mm.
[0059] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention. These improvements and modifications should also be regarded as the scope of protection of the present invention.
Claims
1. A wide spectrum integrated spectrometer based on gradient photonic crystal dispersion, comprising: An optical chip (1) and a CMOS detector (2), characterized in that: the optical chip (1) comprises a beam splitter (101), an optical waveguide, and a gradient photonic crystal (102); the optical waveguide comprises an input optical waveguide (103) and an output optical waveguide (104); the input end of the beam splitter (101) is connected to the input optical waveguide (103); a plurality of output ends of the beam splitter (101) are respectively connected to one end of the output optical waveguide (104); and the other end of each output optical waveguide (104) is respectively connected to the gradient photonic crystal (102); The CMOS detector (2) is used to reconstruct the spatial distribution of scattered light intensity leaked from the gradient photonic crystal (102) to obtain an input spectrum.
2. The wide spectrum integrated spectrometer based on gradient photonic crystal dispersion according to claim 1, characterized in that: The beam splitter (101) is used to split the incident light in the input optical waveguide (103) into a plurality of split beams of light with different wavelengths, and to couple the split beams of light with different wavelengths into corresponding output optical waveguides (104) respectively.
3. The wide spectrum integrated spectrometer based on gradient photonic crystal dispersion according to claim 1, characterized in that: The CMOS detector (2) is placed at the bottom or side of the optical chip (1).
4. The wide spectrum integrated spectrometer based on gradient photonic crystal dispersion according to claim 1, characterized in that: The output optical waveguide (104) is a single-mode optical waveguide, the width of which is determined by the wavelength of the transmitted split beam light.
5. The wide spectrum integrated spectrometer based on gradient photonic crystal dispersion according to claim 1, characterized in that: The gradient photonic crystal (102) comprises a lattice (1021), wherein the lattice (1021) is distributed in an array; and a scattering hole array composed of scattering holes (1022) arranged in a 2x2 matrix is provided on the lattice (1021).
6. The wide spectrum integrated spectrometer based on gradient photonic crystal dispersion according to claim 5, characterized in that: The value of the period dx of the scattering hole array of the lattice (1021) along the waveguide extension direction multiplied by the effective refractive index of the output optical waveguide (104) is 0.5 -0.7 , Indicates the wavelength of the split light in the output optical waveguide (104).
7. The wide spectrum integrated spectrometer based on gradient photonic crystal dispersion according to claim 5, characterized in that: The period dx of the scattering hole array of the lattice (1021) in the gradient photonic crystal (102) along the waveguide extension direction gradually changes from large to small, and the maximum value of the period dx of the scattering hole array along the waveguide extension direction is determined by the longest wavelength of the split light in the output optical waveguide (104), and the minimum value is determined by the shortest wavelength of the split light in the output optical waveguide (104).
8. The wide spectrum integrated spectrometer based on gradient photonic crystal dispersion according to claim 5, characterized in that: The ratio of the diameter D of the scattering holes (1022) of the lattice (1021) to the period dx of the scattering hole array along the waveguide extension direction is 0.
6.
9. The wide spectrum integrated spectrometer based on gradient photonic crystal dispersion according to claim 5, characterized in that: The ratio of the period dy of the scattering hole array of the lattice (1021) perpendicular to the waveguide extension direction to the period dx of the scattering hole array along the waveguide extension direction is 1.
5.
10. The wide spectrum integrated spectrometer based on gradient photonic crystal dispersion according to any one of claims 7 to 9, characterized in that: The expression of the period dx of the scattering hole array along the extension direction of the waveguide is as follows: ； in, represents the effective refractive index of the output optical waveguide (104), The wavelength of the split light in the output optical waveguide (104).