Wide-spectrum integrated spectrometer based on coupling of waveguide grating and scattering array
By coupling the waveguide grating and the scattering array in the spectrometer, the Bloch mode is excited and spatial dispersion is achieved through the scattering array, which solves the problems of effective spatial dispersion in a compact volume and the volume limitation of traditional spectrometers, achieving high resolution and Integrated spectrometer for wide spectral range.
Patent Information
- Application Number
- CN202411456920.4
- 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 prior art is difficult to achieve effective spatial dispersion in a compact volume, and traditional spectrometers require optical path accumulation, resolution is limited by volume, and disordered structures lack design specifications, making processing difficult.
A design based on the coupling of waveguide grating and scattering array is adopted. The waveguide grating is etched on the side of the optical waveguide. The waveguide grating is used to excite the Bloch mode, and further spatial dispersion is achieved through the scattering array. The CMOS detector is used to detect the light intensity distribution to reconstruct the spectrum. .
It achieves an integrated spectrometer with high resolution and wide spectral range in a compact volume, overcoming the volume limitations of traditional spectrometers and the difficulty of processing disordered structures, and is suitable for applications in different wavebands.
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Figure CN119309674A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to a wide spectrum integrated spectrometer based on waveguide grating and scattering array coupling, 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] Therefore, those skilled in the art need to achieve effective spatial dispersion in a compact volume, overcoming the problems of disordered structures having no design specifications, difficult processing, and the need for optical path accumulation in traditional spectrometers. Summary of the invention
[0004] Objective: To overcome the deficiencies in the prior art, the present invention provides a wide spectrum integrated spectrometer based on the coupling of a waveguide grating and a scattering array.
[0005] Technical solution: To solve the above technical problems, the technical solution adopted by the present invention is:
[0006] A wide spectrum integrated spectrometer based on the coupling of a waveguide grating and a scattering array comprises an optical chip and a CMOS detector. The optical chip comprises an optical waveguide, a waveguide grating and a scattering array.
[0007] A waveguide grating is etched on one side of the optical waveguide, and a scattering array is arranged outside the waveguide grating.
[0008] The CMOS detector is used to detect the spatial distribution of scattered light intensity of the scattering array, and reconstruct the incident spectrum using the light intensity distribution.
[0009] The waveguide grating adopts a waveguide grating with a gradual period, and the Bloch modes of incident light of different wavelengths are localized at different spatial positions of the waveguide grating.
[0010] The scattering array comprises scattering units, the scattering units are distributed in an array, the scattering units are composed of nanocolumns arranged in a 2x2 matrix, and the radius of the nanocolumns of the scattering array varies gradually along the extension direction of the optical waveguide.
[0011] As a preferred solution, the CMOS detector is placed at the bottom, top, or side of the scattering array position of the optical chip.
[0012] As a preferred solution, the optical waveguide is a multimode waveguide.
[0013] As a preferred solution, the product of the effective refractive index of the Bloch mode of the incident light of different wavelengths and the grating period of the waveguide grating is an integer multiple of the target wavelength of the spectrometer.
[0014] As a preferred solution, the waveguide grating comprises grating units, the grating units are arranged in sequence, and the ratio of the etched length a of the grating unit to the period Λ of the waveguide grating is 1:2.
[0015] As a preferred solution, the etching depth b of the waveguide grating is set to one fifth of the width of the optical waveguide.
[0016] As a preferred solution, the maximum period of the waveguide grating is determined by the longest wavelength in the wavelength range of the incident light, and the minimum period is determined by the shortest wavelength in the wavelength range of the incident light.
[0017] As a preferred solution, the radius of the nanocolumn is determined by the wavelength of the scattering resonance of the incident light at the local position of the corresponding waveguide grating.
[0018] As a preferred solution, the period dx of the scattering units of the scattering array along the extension direction of the optical waveguide is ten times the period Λ of the waveguide grating corresponding to the position.
[0019] As a preferred solution, the period dy of the scattering unit perpendicular to the extension direction of the optical waveguide is set to 2 microns.
[0020] Beneficial effects: The wide spectrum integrated spectrometer based on the coupling of waveguide grating and scattering array provided by the present invention etches the waveguide grating on the side of the optical waveguide, uses the waveguide grating to excite the Bloch mode, and by modifying the side depth of the waveguide grating and the period of the waveguide grating, it is possible to achieve localization of different wavelengths at different positions of the waveguide grating. A scattering array composed of nanocolumns is designed on the outside of the waveguide grating, and the localized Bloch mode of the waveguide grating is coupled to the scattering array to achieve further spatial dispersion. A CMOS detector is used to detect the light intensity distribution on the side or bottom of the scattering array, and the incident spectrum is reconstructed according to the light intensity distribution.
[0021] Furthermore, the integrated spectrometer design of the present invention combines the Bloch mode localization of the waveguide grating and the scattering array resonance of the nanocolumn array, overcoming the problem that the resolution accuracy of traditional spectrometers is limited by volume, and realizing an integrated spectrometer with high resolution and wide spectral range.
[0022] Furthermore, the key design structures of the present invention are the waveguide grating and the scattering array. The incident light to be measured is coupled into the optical waveguide, and the Bloch mode is excited at the waveguide grating. Light of different wavelengths has different spatial local distributions, which are coupled out by the scattering column array outside the grating and scattered into the free space. Scattering columns of different radii have different scattering effects for different wavelengths. Finally, the spatial distribution of the scattered light is detected by the CMOS detector, and the spectrum is reconstructed according to the spatial distribution. Among them, the period of the waveguide grating changes gradually, and the grating period depends on the target wavelength range. The scattering array is composed of periodically arranged nanocolumns, and the radius of the nanocolumns depends on the wavelength size of the local area at that position. The final actual design parameters need to be determined through simulation.
[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, by adjusting the structural parameters of the waveguide grating and the scattering array, the present invention can be applicable to various bands such as near ultraviolet, visible light, and near infrared, thereby meeting the application requirements of different occasions. BRIEF DESCRIPTION OF THE DRAWINGS
[0027] Figure 1 It is a schematic diagram of the structure of the integrated spectrometer of the present invention.
[0028] Figure 2 It is a schematic diagram of the structure of the optical waveguide and waveguide grating of the present invention.
[0029] Figure 3 It is a schematic diagram of the structure of the optical waveguide, waveguide grating and scattering array of the present invention. 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 the coupling of waveguide grating and scattering array, such as Figure 1 As shown, it includes an optical chip 1 and a CMOS detector 2 . The optical chip 1 includes: an optical waveguide 101 , a waveguide grating 102 and a scattering array 103 .
[0034] A waveguide grating 102 is etched on one side of the optical waveguide 101 , and a scattering array 103 is arranged outside the waveguide grating 102 .
[0035] The CMOS detector 2 is used to detect the spatial distribution of the scattered light intensity of the scattering array, and to reconstruct the incident spectrum using the light intensity distribution.
[0036] Furthermore, in one embodiment, the CMOS detector 2 is placed at the bottom of the optical chip 1 .
[0037] Furthermore, in one embodiment, the CMOS detector 2 is placed on top of the optical chip 1 .
[0038] Furthermore, in one embodiment, the CMOS detector 2 is placed on the side of the scattering array 103 of the optical chip 1 .
[0039] Furthermore, the optical waveguide 101 is a multimode waveguide. The optical waveguide is designed as a single-mode waveguide or a multimode waveguide according to the application scenario. Compared with the single-mode waveguide, the multimode waveguide has lower transmission loss and can be designed with greater spatial dispersion and a wider wavelength response range.
[0040] Furthermore, the waveguide grating 102 adopts a waveguide grating with a gradual period, and the Bloch modes of incident light of different wavelengths are localized at different spatial positions of the waveguide grating.
[0041] Furthermore, the product of the effective refractive index of the Bloch mode of the incident light of different wavelengths and the grating period of the waveguide grating is an integer multiple of the target wavelength of the spectrometer, so that the Bloch mode can be effectively excited.
[0042] Furthermore, the waveguide grating 102 includes grating units 1021, the grating units 1021 are arranged in sequence, and the ratio of the etched length a of the grating units 1021 to the period Λ of the waveguide grating 102 is 1:2.
[0043] Furthermore, the maximum period of the waveguide grating is determined by the longest wavelength in the wavelength range of the incident light, and the minimum period is determined by the shortest wavelength in the wavelength range of the incident light.
[0044] like Figure 2 As shown, the waveguide grating 102 is composed of grating units 1021 with a depth of b, a length of a, and a period of Λ etched sequentially on the optical waveguide side. The incident light of a specific wavelength will be localized as a Bloch mode at the waveguide grating. The Bloch mode can be divided into energy localized in the high refractive index medium at the unetched part of the waveguide grating and energy localized in the air at the etched part between the waveguide gratings. The Bloch mode localized in the medium has a stronger localization effect. When the product of the effective refractive index of the Bloch mode and the period Λ of the waveguide grating is an integer multiple of the target wavelength of the spectrometer, the Bloch mode can be effectively excited.
[0045] By designing the period Λ of the waveguide grating to change gradually, different wavelengths can be localized at different positions. Generally speaking, the ratio of the etching length a of the grating unit to the period Λ of the waveguide grating is fixed at 1 to 2. It should be noted that the etching depth b of the grating unit 1021 refers to the distance extending from the side of the optical waveguide into the waveguide. The area after the grating unit is etched is air and is not filled with other dielectric materials. It should also be noted that Figure 2 As shown in the figure, the change of the period of the actual waveguide grating is negligible compared to the length of the waveguide grating along the propagation direction. Therefore, the period Λ of the waveguide grating has almost no difference locally and can be regarded as an ideal grating with periodic arrangement.
[0046] Furthermore, the scattering array 103 includes scattering units 1031, which are distributed in an array. The scattering units 1031 are composed of nanocolumns 10311 arranged in a 2x2 matrix, and the radius of the nanocolumns 10311 of the scattering array 103 gradually changes in size along the extension direction of the optical waveguide. The local Bloch mode of the grating unit is coupled to the scattering array to achieve further spatial dispersion. Furthermore, the radius of the nanocolumn 10311 is determined by the wavelength of the scattering resonance of the incident light at the local position of the corresponding waveguide grating 102. The nanocolumn has a scattering resonance for incident light of different wavelengths, and the wavelength of the scattering resonance is proportional to the radius of the nanocolumn.
[0047] like Figure 3 As shown, the scattering array is designed outside the optical waveguide, wherein the period of the scattering unit 1031 along the extension direction of the optical waveguide is dx, the period perpendicular to the extension direction of the optical waveguide is dy, and the radius of the nanocolumn is r.
[0048] Furthermore, the optical chip 1 further comprises a base layer 104 , the top surface of which is provided with an optical waveguide 101 , a waveguide grating 102 and a scattering array 103 , and the base layer 104 is made of silicon dioxide.
[0049] Embodiment 2:
[0050] This embodiment takes the target wavelength range of the spectrometer as 400nm-800nm visible light band as an example. The incident light to be measured is coupled into the optical waveguide, and the Bloch mode is excited at the waveguide grating. Incident light of different wavelengths has different spatial local distributions. The spatial local distribution is coupled by the scattering array outside the waveguide grating and scattered into the free space. Nanocolumns of different radii have different scattering effects for different wavelengths. Finally, the spatial distribution of the scattered light is detected by the CMOS detector placed on the bottom of the optical chip, and the spectrum is reconstructed according to the spatial distribution.
[0051] To ensure that the Bloch mode is bound in the waveguide grating, the optical waveguide and the waveguide grating adopt a layered structure of magnesium fluoride material, the thickness of the layered structure is at least more than 1 micron, and the nanocolumn adopts PMMA (acrylic) material, and the thickness of the nanocolumn is 300 nanometers. The width of the optical waveguide is set to 2 microns, according to the relationship between the effective refractive index of the Bloch mode and the grating period of the waveguide grating ,λ is the wavelength of the incident light in the waveguide grating, n eff To obtain the effective refractive index of the Bloch mode, the grating period dx of the waveguide grating should be gradually increased from 148nm to 296nm.
[0052] The duty cycle of the waveguide grating is designed to be 0.5, and the side depth b is set to one fifth of the optical waveguide width, i.e. 400 nm.
[0053] According to the local characteristic wavelength of the nanocolumn location and the correspondence between the radius and the resonance wavelength calculated in advance by simulation software, a table is looked up to design a gradual change in the nanocolumn radius from 300nm to 400nm.
[0054] The scattering array period dx is ten times the period Λ of the waveguide grating at the location, and the period dy is set to 2 microns. This structure makes full use of the spatial localization of the waveguide grating Bloch mode and the scattering resonance characteristics of the nanocolumns, making the optical chip size within 0.5mm×1mm and achieving a wavelength resolution of 2nm in the wavelength range of 400nm-800nm.
[0055] 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 waveguide grating coupled with a scattering array, comprising: An optical chip (1) and a CMOS detector (2), characterized in that the optical chip (1) comprises an optical waveguide (101), a waveguide grating (102) and a scattering array (103); A waveguide grating (102) is etched on one side of the optical waveguide (101), and a scattering array (103) is arranged on the outside of the waveguide grating (102); The CMOS detector (2) is used to detect the spatial distribution of scattered light intensity of the scattering array, and to reconstruct the incident spectrum using the light intensity distribution; The waveguide grating (102) adopts a waveguide grating with a gradual period, and the Bloch modes of incident light of different wavelengths are localized at different spatial positions of the waveguide grating; The scattering array (103) comprises scattering units (1031), the scattering units (1031) are distributed in an array, the scattering units (1031) are composed of nanocolumns (10311) arranged in a 2x2 matrix, and the radius of the nanocolumns (10311) of the scattering array (103) varies gradually along the extension direction of the optical waveguide.
2. The wide spectrum integrated spectrometer based on waveguide grating coupled with scattering array according to claim 1, characterized in that: The CMOS detector (2) is placed at the bottom, top, or side of the optical chip (1) at the location of the scattering array (103).
3. The wide spectrum integrated spectrometer based on waveguide grating coupled with scattering array according to claim 1, characterized in that: The optical waveguide (101) is a multimode waveguide.
4. The wide spectrum integrated spectrometer based on waveguide grating coupled with scattering array according to claim 1, characterized in that: The product of the effective refractive index of the Bloch mode of the incident light of different wavelengths and the grating period of the waveguide grating (102) is an integer multiple of the target wavelength of the spectrometer.
5. The wide spectrum integrated spectrometer based on waveguide grating coupled with scattering array according to claim 1, characterized in that: The waveguide grating (102) comprises grating units (1021), the grating units (1021) are arranged in sequence, and the ratio of the etched length a of the grating units (1021) to the period Λ of the waveguide grating (102) is 1 to 2.
6. The wide spectrum integrated spectrometer based on waveguide grating coupled with scattering array according to claim 1, characterized in that: The etching depth b of the waveguide grating (102) is set to one fifth of the width of the optical waveguide (101).
7. The wide spectrum integrated spectrometer based on waveguide grating coupled with scattering array according to claim 1, characterized in that: The maximum period of the waveguide grating (102) is determined by the longest wavelength in the wavelength range of the incident light, and the minimum period is determined by the shortest wavelength in the wavelength range of the incident light.
8. The wide spectrum integrated spectrometer based on waveguide grating coupled with scattering array according to claim 1, characterized in that: The radius of the nanocolumn (10311) is determined by the wavelength of the scattering resonance of the incident light localized at the position of the corresponding waveguide grating (102).
9. The wide spectrum integrated spectrometer based on waveguide grating coupled with scattering array according to claim 1, characterized in that: The period dx of the scattering units (1031) of the scattering array (103) along the extension direction of the optical waveguide is ten times the period Λ of the waveguide grating corresponding to the position.
10. The wide spectrum integrated spectrometer based on waveguide grating coupled with scattering array according to claim 1, characterized in that: The period dy of the scattering unit (1031) perpendicular to the extension direction of the optical waveguide is set to 2 microns.