WO2023284143A1 - 基于双层螺旋波导的片上傅里叶变换光谱仪 - Google Patents

基于双层螺旋波导的片上傅里叶变换光谱仪 Download PDF

Info

Publication number
WO2023284143A1
WO2023284143A1 PCT/CN2021/123482 CN2021123482W WO2023284143A1 WO 2023284143 A1 WO2023284143 A1 WO 2023284143A1 CN 2021123482 W CN2021123482 W CN 2021123482W WO 2023284143 A1 WO2023284143 A1 WO 2023284143A1
Authority
WO
WIPO (PCT)
Prior art keywords
double
waveguide
layer
fourier transform
chip
Prior art date
Application number
PCT/CN2021/123482
Other languages
English (en)
French (fr)
Inventor
陆梁军
成天宇
周林杰
陈建平
刘娇
Original Assignee
上海交通大学
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by 上海交通大学 filed Critical 上海交通大学
Publication of WO2023284143A1 publication Critical patent/WO2023284143A1/zh
Priority to US18/413,015 priority Critical patent/US20240337536A1/en

Links

Images

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/01—Arrangements or apparatus for facilitating the optical investigation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/45—Interferometric spectrometry
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
    • G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
    • G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
    • G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
    • G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/21—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  by interference
    • G02F1/212—Mach-Zehnder type
    • G—PHYSICS
    • G02—OPTICS
    • G02F—OPTICAL DEVICES OR ARRANGEMENTS FOR THE CONTROL OF LIGHT BY MODIFICATION OF THE OPTICAL PROPERTIES OF THE MEDIA OF THE ELEMENTS INVOLVED THEREIN; NON-LINEAR OPTICS; FREQUENCY-CHANGING OF LIGHT; OPTICAL LOGIC ELEMENTS; OPTICAL ANALOGUE/DIGITAL CONVERTERS
    • G02F1/00—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics
    • G02F1/01—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour 
    • G02F1/21—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  by interference
    • G02F1/225—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  by interference in an optical waveguide structure
    • G02F1/2252—Devices or arrangements for the control of the intensity, colour, phase, polarisation or direction of light arriving from an independent light source, e.g. switching, gating or modulating; Non-linear optics for the control of the intensity, phase, polarisation or colour  by interference in an optical waveguide structure in optical fibres
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J3/00—Spectrometry; Spectrophotometry; Monochromators; Measuring colours
    • G01J3/28—Investigating the spectrum
    • G01J3/45—Interferometric spectrometry
    • G01J3/453—Interferometric spectrometry by correlation of the amplitudes
    • G01J2003/4538—Special processing

Definitions

  • the invention belongs to the field of light detection and sensing, in particular to an on-chip Fourier transform spectrometer based on a double-layer spiral waveguide.
  • Infrared spectrometer is one of the most effective means of chemical analysis, which uses the absorption characteristics of infrared radiation of different wavelengths to realize the analysis and identification of molecular structure and chemical composition.
  • Traditional Fourier transform spectrometers usually composed of discrete optical elements and mechanical parts, are costly, large in size, and inconvenient to carry and use.
  • the Michelson interferometer needs to change the optical path difference by moving the mirror to generate interference fringes.
  • the research on miniaturized on-chip Fourier transform spectrometer has received extensive research and attention.
  • the reported Fourier transform spectrometer based on MEMS has achieved system miniaturization (see Opt.Lett., vol.24, no.23, pp.1705-1707, 1999), but still contains relatively fragile moving parts, preferably without any moving parts.
  • the existing on-chip Fourier transform spectrometers can be mainly divided into two categories: standing wave integrated Fourier transform (SWIFT) spectrometers and spatial heterodyne spectrometers (SHS).
  • WIFT standing wave integrated Fourier transform
  • SHS spatial heterodyne spectrometers
  • the SWIFT-based spectrometer generates standing wave interference fringes through two oppositely transmitted light beams in the waveguide, and receives the interference pattern of waveguide scattered light by arranging a detector array above the waveguide.
  • Such devices only require a small chip size to achieve high precision.
  • the spacing of the interference fringes is ⁇ /2n eff , which is much smaller than the spacing of existing detector arrays. Therefore, the measured interferogram is under-sampled, resulting in limited spectral bandwidth (see Nat. Photon., vol. 1, p. 473-478, 2007.).
  • the existing solutions all receive interference fringes by placing an infrared camera above the waveguide, so it is difficult to miniaturize the entire system.
  • Spectrometers based on the SHS structure generally generate space-transformed interference patterns by changing the arm length difference or optical path difference of an asymmetric Mach-Zehnder interferometer (MZI).
  • MZI Mach-Zehnder interferometer
  • there are two main ways to achieve optical path difference modulation one is to change the effective optical path of one of the arms through the electro-optic effect and thermo-optic effect, and the other is to generate interference through a series of MZI arrays with different optical path differences pattern.
  • the refractive law and length of the waveguide produced by thermo-optic or electro-optical effect modulation have small changes and high power consumption.
  • the thermo-optical nonlinearity, thermal expansion and dispersion caused by heating will introduce errors in spectral reconstruction, and the change of ambient temperature will also affect the heating and test results of the device.
  • the number of MZIs can be increased to improve the resolution of a given spectral bandwidth, but it also fails to solve the problem of thermal sensitivity.
  • the test temperature changes, due to the change of the waveguide refraction law and the change of the waveguide length, the final result will be The translation of the interference fringe affects the reconstruction accuracy of the spectrum.
  • the different lengths of the MZI arms will introduce different losses, the greater the length difference, the greater the loss, resulting in a smaller extinction ratio.
  • the on-chip Fourier transform spectrometer based on integrated optical waveguide has become a research hotspot and has been continuously improved since it was proposed in 2007, but it is also subject to many factors such as temperature sensitivity.
  • the existing on-chip Fourier transform spectrometer has a large gap with the existing advanced desktop Fourier transform spectrometer in terms of effective resolution points, spectral range and practicality.
  • the present invention provides an on-chip Fourier transform spectrometer based on a double-layer helical waveguide.
  • the invention utilizes the difference in refraction laws of odd and even mode groups in the double-layer spiral waveguide to construct a non-equal Mach-Zehnder interferometer structure, which has the advantages of good chip temperature stability, high output extinction ratio, and the like.
  • the resolution of the chip can be effectively improved through compressed sampling technology and spectral reconstruction algorithm.
  • An on-chip Fourier transform spectrometer based on a double-layer spiral waveguide is characterized in that it includes a waveguide input coupler, a 1 ⁇ N optical beam splitter, N double-layer waveguide Y-branch structures, N double-layer spiral waveguides, N reversely placed double-layer waveguide Y-branch structures and N silicon-germanium detectors;
  • the output end of the waveguide input coupler is connected to the input end of the 1 ⁇ N optical beam splitter, and the N output ends of the 1 ⁇ N optical beam splitter are respectively connected to the N double-layer waveguide Y
  • One input end of the bifurcated structure is connected, the output end of the N double-layer waveguide Y bifurcated structure is connected to the input end of the N double-layer helical waveguides, and the output of the N double-layer helical waveguides
  • the end is connected to the input ends of N reversely placed double-layer waveguide Y bifurcated structures, and one output end of the N reversely placed double-layer waveguide Y-branched structures is connected to the N silicon-germanium detectors
  • the input terminal is connected;
  • the N double-layer helical waveguides are composed of N double-layer helical waveguides whose length increases linearly, the two-layer waveguides of each double-layer helical waveguide are parallel to each other, and the width and height of each double-layer helical waveguide are the same as the corresponding
  • the waveguide input coupler adopts an end-face coupler structure or a grating coupler structure, and the spectral signal to be measured is coupled into the chip through an optical fiber.
  • the 1 ⁇ N optical beam splitter realizes equal distribution of incident optical power, and can adopt a log 2 N-level cascaded 1 ⁇ 2 beam splitter structure, and the 1 ⁇ 2 beam splitter can use Y bifurcation, directional coupler or Multi-mode interferometer (MMI) and other structures; or directly adopt a 1 ⁇ N multi-mode interferometer structure.
  • MMI Multi-mode interferometer
  • the N double-layer waveguide Y-branch structures and the N double-layer waveguide Y-branch structures placed in reverse are all composed of N double-layer waveguide Y-branch structures of the same structure.
  • the upper and lower waveguides have the same width and thickness and are parallel to each other, that is, the double-layer waveguides together form the beam-combining end; at the bifurcation, the upper and lower vertical waveguides gradually separate in the horizontal direction, and each becomes a single-layer waveguide. Splitting of incident light and conversion of waveguides from bilayer to monolayer.
  • the N silicon germanium detectors can adopt a silicon germanium PIN structure to convert optical power signals into electrical signals.
  • the N double-layer waveguide Y-fork structures, N double-layer helical waveguides with increasing lengths and N reversely placed double-layer waveguide Y-fork structures constitute a non-equivalent Mach-
  • the Zender interferometer array structure realizes the function of spatial heterodyne coherent Fourier transform spectrometer.
  • the double-layer helical waveguide array constitutes a waveguide structure that produces different optical path differences, and the optical path difference varies according to the helical length of a single waveguide in the double-layer helical waveguide structure array.
  • the spectrum test In the spectrum test, light sources of different wavelengths are input to test the optical power received by the silicon germanium detector array, and then the calibration matrix is obtained after normalization adjustment.
  • the optical power measured by the silicon germanium detector array is used, and the compressed sensing algorithm is used to set reasonable regularization parameters and hyperparameters for spectral reconstruction, thereby improving spectral resolution.
  • the present invention has beneficial effects mainly reflected in the following aspects:
  • the double-layer spiral waveguide structure of this device is made of silicon nitride material, which has a small thermo-optic coefficient.
  • the optical path difference OPD i L i (n gO -n ge ) of the odd and even mode excitation generated by the double-layer spiral waveguide structure of this device, n go and n ge are respectively the groups of the odd-even mode excitation in the double-layer spiral waveguide Refractive index, L i is the length of the ith helical waveguide.
  • thermo-optic coefficients of the excitation of the odd and even modes in the double-layer spiral waveguide are close, and when the temperature changes, the effective refractive index changes of the two can be approximately canceled.
  • this structure has the advantage of being insensitive to temperature.
  • the propagation lengths of the odd and even modes are the same, and the mode distributions of the odd and even modes are similar. Therefore, the loss of the two is similar, and it has the advantage of a higher output interference fringe extinction ratio.
  • Fig. 1 is a schematic structural diagram of a Fourier transform spectrometer on a silicon substrate of the present invention.
  • Fig. 2 is a schematic diagram of a three-dimensional Y-forked structure according to an embodiment of the present invention.
  • Fig. 3 is a schematic diagram (top view) of the double-layer helical waveguide structure of the present invention.
  • Fig. 4 is a schematic diagram (side view) of the double-layer helical waveguide structure of the present invention.
  • FIG. 6 is a schematic diagram of a typical calibration matrix A of an embodiment of the present invention.
  • Figure 7 is an example diagram of the dual-wavelength recovery spectrum of the embodiment of the present invention.
  • Fig. 1 is the structure schematic diagram of Fourier transform spectrometer on the silicon substrate of the present invention, as can be seen from the figure, the present invention is based on the Fourier transform spectrometer on the chip of double-layer helical waveguide, and this chip comprises waveguide input coupler 1001, 1 ⁇ N optical beam splitters 1002, N double-layer waveguide Y-branch structures 1003, N double-layer helical waveguides 1004 with increasing lengths, N reverse-placed double-layer waveguide Y-branch structures 1005, and N silicon-germanium detectors 1006, prepared in silicon-on-insulator material, the waveguide adopts silicon nitride material, the output end of the waveguide input coupler 1001 is connected to the input end of the 1 ⁇ N optical beam splitter 1002; the 1 ⁇ N optical beam splitter 1002 is connected; The N output ends of the N optical beam splitter 1002 are respectively connected to one input end of the N double-layer waveguide Y bifurcated structures 1003; the output
  • the waveguide input coupler 1001 adopts an end-face coupler structure, and its purpose is to couple the spectral signal to be measured into the chip through an optical fiber.
  • the output end of the waveguide input coupler is connected to the input end of the 1 ⁇ 32 optical beam splitter.
  • the 1 ⁇ 32 beam splitter 1002 adopts a 5-stage cascaded 1 ⁇ 2 beam splitter structure, wherein the 1 ⁇ 2 beam splitter adopts a multimode interferometer (MMI).
  • MMI multimode interferometer
  • the 32 double-layer waveguide Y-branch structures 1003 and the 32 reverse-placed double-layer waveguide Y-branch structures 1005 are both composed of N double-layer waveguide Y-branch structures 2001 of the same structure.
  • the structure of the Y bifurcated structure 2001 is shown in Figure 2. It is composed of two vertically placed waveguides with a width of 1 ⁇ m and a thickness of 400 nm at the beam combining place.
  • the beam-combining end 2002 is formed; at the bifurcation, the upper and lower vertical waveguides are gradually separated in the horizontal direction, and become single-layer waveguides 2003 and 2004 respectively, so as to realize the splitting of incident light and the conversion of the waveguide from double-layer to single-layer.
  • the 32 output ports of the 1 ⁇ 32 optical beam splitter 1002 are respectively connected to one input port of 32 double-layer waveguide Y-branch structures 1003; the output ports of the 32 double-layer waveguide Y-branch structures 1003 are connected to 32
  • the input ends of the double-layer helical waveguides 1004 are connected; the output ends of 32 double-layer helical waveguides 1004 with increasing lengths are connected with the input ends of 32 reversely placed double-layer waveguide Y-branch structures 1005 .
  • the 32 double-layer helical waveguides 1004 have increasing lengths, and are composed of 32 double-layer silicon nitride helical waveguides 3001 with linearly increasing lengths; the two-layer silicon nitride waveguides are arranged in the vertical direction, and the waveguide width and height are bifurcated with Y
  • the structure is consistent with 2001.
  • the final output optical signal is measured by the silicon germanium detector, which is connected to the output port of the double-layer helical waveguide, and converts the optical power signal of the interference light into an electrical signal.
  • the structure of the double-layer helical waveguide is shown in Figure 3.
  • a silicon nitride material with a small thermo-optic coefficient is used when selecting materials.
  • ⁇ n eff represents the effective refractive index difference n effO -n effe of odd and even mode excitation in the waveguide, so Thermo-optic coefficient difference in a silicon nitride waveguide for odd and even mode excitation.
  • the input light is coupled from the lower waveguide to the upper waveguide through the coupling effect, and propagates in the form of odd and even mode excitation in the upper silicon nitride waveguide. Since the distribution of odd and even mode excitations in the upper waveguide is similar, the thermo-optic coefficients of the two in the silicon nitride waveguide are similar, so Smaller to achieve athermal testing and calibration within the test bandwidth.
  • the Fourier transform spectrometer needs to be calibrated to obtain the calibration matrix of the chip.
  • Input the monochromatic light to the input end of the chip you can get 32 interference light outputs, measure the optical power values of these interference lights, and get 32 optical power values as a column of the matrix.
  • Change the wavelength of the monochromatic light perform step-by-step scanning, and test m times of different incremental wavelengths to obtain a 32 ⁇ m matrix, and normalize the matrix to obtain the calibration matrix A.
  • the wavelength range is 1562.5nm-1577.5nm
  • the step size is 0.015nm.
  • the solution of x in the matrix equation is not unique.
  • the invention adopts a machine learning algorithm to accurately reconstruct the spectrum to be measured. Since some of the spectra to be measured are sparse (only a few discrete wavelength components), and some are continuous spectra, different algorithms should be used depending on the situation when restoring. Among them, the L 1 norm term is mainly used to increase the sparsity, and the L 2 norm term is mainly used to increase the smoothness of the amplitude, and the above two items have a good effect on reconstructing the sparse spectrum.
  • the invention can meet the miniaturization and portability application requirements of the Fourier transform spectrometer, and can solve the temperature-sensitive problem of the existing spectrometer on a silicon substrate.
  • the above content is the specific implementation scheme of the present invention, the Fourier transform spectrometer chip on the silicon substrate, which can be easily understood by those in the same field of scientific research or industry.
  • the above content is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention within.

Landscapes

  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Nonlinear Science (AREA)
  • Optics & Photonics (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Biochemistry (AREA)
  • General Health & Medical Sciences (AREA)
  • Immunology (AREA)
  • Pathology (AREA)
  • Spectrometry And Color Measurement (AREA)

Abstract

一种基于双层螺旋波导的片上傅里叶变换光谱仪，依次包括波导输入耦合器（1001）、1×N光分束器（1002）、N个双层波导Y分叉结构（1003）、N个长度递增的双层螺旋波导（1004）、N个反向放置的双层波导Y分叉结构（1005）和N个锗硅探测器（1006）。利用双层波导中奇模和偶模的群折射率差来构成非等臂马赫-增德尔干涉器结构，利用N个长度递增的双层螺旋波导（1004）实现基于空间外差相干的傅里叶变换光谱仪，测得的干涉条纹通过回归算法实现光谱重建。能满足傅里叶变换光谱仪对于小型化、便携化的应用需求，并能够解决现有硅基片上光谱仪对温度敏感的问题。

Description

基于双层螺旋波导的片上傅里叶变换光谱仪 技术领域
本发明属于光检测和传感领域，特别是一种基于双层螺旋波导的片上傅里叶变换光谱仪。
背景技术
红外光谱仪利用物质对不同波长的红外辐射吸收特性实现分子结构和化学组成的分析和识别，是化学分析的最有效手段之一。传统的傅里叶变换光谱仪，通常由分立的光学元件和机械部件组成，成本高、尺寸大、携带和使用不方便。例如迈克尔逊干涉仪，需要通过移动反射镜改变光程差来产生干涉条纹。为了压缩体积、减小成本、降低功耗、方便携带与使用，小型化片上傅里叶变换光谱仪的研究受到了广泛的研究和关注。已报道的基于微机电系统(MEMS)的傅里叶变换光谱仪实现了系统小型化(参见Opt.Lett.,vol.24,no.23,pp.1705-1707,1999)，但仍旧包含相对脆弱的移动组件，最好方案是无任何可移动组件。
近来年，随着集成光电子技术的不断进步，尤其是硅基光电子技术的高速发展，光电子芯片中器件集成度和功能复杂度不断增长，集成光电子芯片的应用领域也不再局限于光通信，更是拓展至自动驾驶、光子神经网络、量子信号处理、生物传感等领域。对片上傅里叶变换光谱仪的研究逐渐成为热点，它无任何运动部件，具有尺寸小、重量轻、功耗和低成本等优点，可以满足未来生物检测、宇宙粒子检测等领域的芯片实验室(Lab-on-a-chip)应用需求。
现有片上傅里叶变换光谱仪主要可以分为两类：驻波集成傅里叶变换(SWIFT)光谱仪和空间外差光谱仪(SHS)。
基于SWIFT的光谱仪通过波导中两个对向传输的光束来产生驻波干涉条纹，通过在波导上方排布探测器阵列来接收波导散射光的干涉图谱。该类器件只需要较小的芯片尺寸就可实现高精度。但是根据E.Coarer等人的研究工作表明，干涉条纹的间距为λ/2n eff，远小于现有探测器阵列的间距。因此，测得的干涉图是欠采样的，导致光谱带宽受限(参见Nat.Photon.,vol.1,p.473-478,2007.)。并且，现有方案都是通过在波导上方放置红外相机来接收干涉条纹，因此很难实现整个系统的小型化。
基于SHS结构的光谱仪，一般通过改变非对称马赫-增德尔干涉器(MZI)的臂长差或者光程差来产生空间变换的干涉图样。目前主要有两种方式来实现光程差调制，一种是通过电光效应和热光效应来改变其中一个臂的有效光程，另一种是通过一系列不同光程差的MZI阵列来产生干涉图样。基于第一种方式，利用热光或电光效应调制产生的波导折射律及长度变化较小，功耗较大。另外，由于引入了热调，加热引起的热光非线性、热膨胀和色散会给光谱重建引入误差，环境温度的变化也会给器件的加热与测试结果带来影响。对于第二种方式可以增加MZI数量提高给定光谱带宽的分辨率，但也同样未能解决热敏感性的问题，测试温度变化时，由于波导折射律的改变以及波导长度的变化，会导致最终干涉条纹的平移，影响到光谱的重构精度。此外，由于MZI臂长不同会引入不同的损耗，长度差越大损耗越大，最终导致消光比较小。
此外，近年来，诸多科研人员提出了不同的方案来提高片上傅里叶变换光谱仪的性能，如在MZI干涉臂上分别集成光开关以实现光程差的数字式调制(参见Nat.Commun.,vol.9,2018.)，利用波导的偏振来减少MZI的数目(参见Opt.Lett.,vol.44,no.11,pp.2923-2926,2019.)，利用温度相关校准矩阵来减低温度敏感性等(参见Opt.Lett.,vol.42,no.11,pp.2239-2242,2017.)。
可以看出，基于集成光波导的片上傅里叶变换光谱仪自2007年提出以来，在成为研究热点、得到不断改进的同时，也受制于温度敏感性等诸多因素。现有的片上傅里叶变换光谱仪在有效分辨点数、光谱范围以及实际性等方面，都与现有先进台式傅里叶变换光谱仪有较大的差距。
发明内容
针对上述现有实现方案中存在的缺陷，本发明提供一种基于双层螺旋波导的片上傅里叶变换光谱仪。本发明利用双层螺旋波导中奇偶模群折射律差来构建非等臂马赫-增德尔干涉器结构，具有芯片温度稳定性好、输出消光比高等优点。此外，通过压缩采样技术和光谱重构算法，可有效提高芯片的分辨率。
为实现上述目的，本发明的技术解决方案如下：
一种基于双层螺旋波导的片上傅里叶变换光谱仪，其特点在于，包括波导输入耦合器、1×N光分束器、N个双层波导Y分叉结构、N个双层螺旋波导、N个反向放置的双层波导Y分叉结构和N个锗硅探测器；
所述的波导输入耦合器的输出端与所述的1×N光分束器的输入端相连，该1×N光分束器的N个输出端分别与所述的N个双层波导Y分叉结构的一个输入端相连， 所述的N个双层波导Y分叉结构的输出端与所述的N个双层螺旋波导的输入端相连，所述的N个双层螺旋波导的输出端与N个反向放置的双层波导Y分叉结构的输入端相连，所述的N个反向放置的双层波导Y分叉结构的一个输出端与所述的N个锗硅探测器的输入端相连；
所述的N个双层螺旋波导由N个长度线性递增的双层螺旋波导构成，每个双层螺旋波导的两层波导相互平行，且每个双层螺旋波导的宽度和高度与相对应的双层波导Y分叉结构的宽度和高度一致，所述的双层螺旋波导具有不同的群折射律的偶模和奇模，使得输出端有不同的光程差OPD i＝L i(n gO-n ge)，n go与n ge分别为奇模、偶模激励在双层螺旋波导中的群折射系数，L i为第i个双层螺旋波导长度。
所述波导输入耦合器，采用端面耦合器结构或光栅耦合器结构，待测光谱信号通过光纤耦合输入芯片中。
所述的1×N光分束器实现入射光功率均分，可采用log 2N级的级联1×2分束器结构，1×2分束器可采用Y分叉、定向耦合器或多模干涉器(MMI)等结构；或者直接采用1×N多模干涉器结构。
所述的N个双层波导Y分叉结构和N个反向放置的双层波导Y分叉结构都由N个相同结构的双层波导Y分叉结构构成，该Y分叉结构在合束处由上下两个宽度相同、厚度相同且相互平行的波导构成，即双层波导共同构成了合束端；在分叉处上下两个垂直波导在水平方向逐渐分开，各自成为单层波导，实现入射光的分光以及波导从双层到单层的转换。
所述的N个锗硅探测器，可采用锗硅PIN结构，将光功率信号转换为电信号。
所述的N个双层波导Y分叉结构、N个长度递增的双层螺旋波导和N个反向放置的双层波导Y分叉结构构成了类似具有递增光程差的非等臂马赫-增德尔干涉器阵列结构，实现空间外差相干的傅里叶变换光谱仪功能。双层螺旋波导阵列构成产生不同光程差的波导结构，光程差变化根据双层螺旋波导结构阵列中单个波导的螺旋长度变化。
光谱测试先通过输入不同波长的光源，测试锗硅探测器阵列接收的光功率，进而进行归一化调整后得到校准矩阵。在对待测光进行测试时，利用锗硅探测器阵列测得的光功率，采用压缩感知算法，设置合理的正则化参数和超参数进行光谱重构，进而提升光谱分辨率。
本发明和现有技术相比，有益效果主要体现在如下方面：
1、本器件的双层螺旋波导结构采用氮化硅材料，热光系数较小。此外，本器件的双层螺旋波导结构产生的奇偶模激励的光程差OPD i＝L i(n gO-n ge)，n go与n ge分 别为奇偶模激励在双层螺旋波导中的群折射系数，L i为第i个螺旋波导长度。由于奇偶模在双层结构中分布接近，说明在双层螺旋波导中奇偶模激励的热光系数接近，在温度改变的时候，两者的有效折射率变化可以近似相消。相对于其他方案，该结构具有温度不敏感的优点。
2、在本发明的单个双层螺旋波导结构中，奇偶模传播的长度相同，且奇偶模的模式分布相近。因此两者损耗相近，具有输出干涉条纹消光比较高的优点。
附图说明
图1为本发明硅基片上傅里叶变换光谱仪结构示意图。
图2为本发明实施例的三维Y分叉结构示意图。
图3为本发明双层螺旋波导结构示意图(俯视)。
图4为本发明双层螺旋波导结构示意图(侧视)。
图5为本发明实施例N＝32时的片上傅里叶变换光谱仪的工作原理图。
图6为本发明实施例的典型的校准矩阵A的示意图
图7为本发明实施例的双波长恢复光谱示例图
具体实施方式
为了进一步阐明本方案的目的、技术方案及核心优势，下文结合附图和实施例，对本发明进行进一步详细说明。请注意，下述具体实施例仅起解释目的，并不用于限定本发明。同时，各个实施例涉及到的技术特征只要彼此未构成冲突，就可以相互结合。
参考图1，图1为本发明硅基片上傅里叶变换光谱仪结构示意图，由图可见，本发明基于双层螺旋波导的片上傅里叶光谱仪，该芯片依次包括波导输入耦合器1001、1×N光分束器1002、N个双层波导Y分叉结构1003、N个长度递增的双层螺旋波导1004、N个反向放置的双层波导Y分叉结构1005和N个锗硅探测器1006，制备在绝缘体上硅材料中，波导采用氮化硅材料，所述的波导输入耦合器1001的输出端与所述的1×N光分束器1002的输入端相连；所述的1×N光分束器1002的N个输出端分别与所述的N个双层波导Y分叉结构1003的一个输入端相连；所述的N个双层波导Y分叉结构1003的输出端与所述的N个长度递增的双层螺旋波导1004的输入端相连；所述的N个长度递增的双层螺旋波导1004的输出端与N个反向放置的双层波导Y分叉结构1005的输入端相连；所述的N个反向放置的双层波导Y 分叉结构1005的一个输出端与所述的N个锗硅探测器1006的输入端相连。
实施例
本发明实施例采用N＝32，其结构如图4所示。
波导输入耦合器1001采用端面耦合器结构，其目的是将待测光谱信号通过光纤耦合输入芯片中，波导输入耦合器的输出端与1×32光分束器的输入端相连。
1×32光分束器1002采用5级的级联1×2分束器结构，其中1×2分束器采用多模干涉器(MMI)。
32个双层波导Y分叉结构1003和32个反向放置的双层波导Y分叉结构1005都由N个相同结构的双层波导Y分叉结构2001构成。该Y分叉结构2001的结构如图2所示，其在合束处由上下两个宽度为1μm，厚度400nm的波导垂直放置构成，两个波导的间距设置为250nm，即双层波导共同构成了合束端2002；在分叉处上下两个垂直波导在水平方向逐渐分开，各自成为单层波导2003,2004，实现入射光的分光以及波导从双层到单层的转换。1×32光分束器1002的32个输出端分别与32个双层波导Y分叉结构1003的一个输入端相连；32个双层波导Y分叉结构1003的输出端与32个长度递增的双层螺旋波导1004的输入端相连；32个长度递增的双层螺旋波导1004的输出端与32个反向放置的双层波导Y分叉结构1005的输入端相连。
32个双层螺旋波导1004的长度递增，由32个长度线性递增的双层氮化硅螺旋波导3001构成；两层氮化硅波导在竖直方向上排布，波导宽度和高度与Y分叉结构2001一致。双层螺旋波导中存在偶模和奇模两个超模，由于偶模和奇模具有不同的群折射律，在输出端口有不同的光程差OPD i＝L i(n gO-n ge)，n go与n ge分别为奇偶模激励在双层螺旋波导中的群折射系数，L i为第i个螺旋波导长度，为600×iμm。由于双层螺旋波导的长度线性递增，奇偶模的光程差也线性递增。
最终输出的光信号由锗硅探测器测得，其与双层螺旋波导的输出端口相连，将干涉光的光功率信号转换为电信号。
在上述方案的基础上，双层螺旋波导的结构如图3所示。为了消除温度敏感性，在选取材料的时候采用热光系数较小的氮化硅材料。该设计的光程差为OPD i＝L i(n gO-n ge)，n go与n ge分别为奇偶模激励在双层螺旋波导中的群折射系数，L i为第i个螺旋波导长度。因此，该器件的温度相关相位差的表达式
Figure PCTCN2021123482-appb-000001
其中，Δn eff表示奇偶模激励在波导中的有效折射率差n effO-n effe，因此
Figure PCTCN2021123482-appb-000002
为奇 偶模激励在氮化硅波导中的热光系数差。输入光通过耦合作用从下层波导耦合到上层波导中，在上层氮化硅波导中以奇偶模激励的形式传播。由于奇偶模激励在上层波导中分布情况相似，两者在氮化硅波导中的热光系数相近，所以
Figure PCTCN2021123482-appb-000003
较小，从而实现测试带宽内的无热化测试与校准。
在上述方案的基础上，在进行正式测试前，需要对傅里叶变换光谱仪进行校准，得到芯片的校准矩阵。将单色光输入到芯片的输入端，可以得到32个干涉光输出，测量这些干涉光的光功率值，得到32个光功率值，作为矩阵的一列。改变单色光的波长，进行步进扫谱，共测试m次不同的递增波长，得到32×m的矩阵，对矩阵进行归一化处理，得到校准矩阵A。如图5所示，波长范围为1562.5nm～1577.5nm，步长为0.015nm。此时波长的还原转化为对式子y＝Ax的求解，其中x为待测的多色光信号，y为测得的干涉图谱，是一个具有32个元素的向量，向量中对应元素的比例表示对应波长单色光在待测多色光中的比例。因此，只需要从y中求得x，就可以恢复出待测多色光的光谱信息。
由于双层螺旋波导的个数有限，远小于扫谱所用的波长个数m，从而矩阵方程中的x解不唯一。本发明采用机器学习算法来准确地重构出待测光谱。由于待测光谱中有部分具有稀疏性(仅有若干离散波长分量)，有部分则是连续光谱，因此在还原时要视情况而定采用不同算法。其中，L 1范数项主要用于增加稀疏性，L 2范数项主要增加幅度的平滑性，上述两项对重构稀疏光谱具有较好的效果。但是由于缺乏对于光谱连续性的约束，仅包含L 1和L 2范数项无法准确恢复出连续光谱。引入光谱的一阶差分矩阵D 1x的L 2范数项可以在一定程度上增加光谱连续性。因此上述若干算法中，采用Elastic-D1算法能够较准确的重构出各类不同的光谱。但是，由于需要计算3个超参数α 1～α 3的值，计算复杂度有所增加。不过该算法中各项都大于0，可以用标准的凸优化工具来计算。图6为采用Lasso算法的典型的双波长入射光还原光谱，入射光中的两种单色光光功率值为1：1。
Figure PCTCN2021123482-appb-000004
Figure PCTCN2021123482-appb-000005
表1
实验表明，本发明能满足傅里叶变换光谱仪对于小型化、便携化的应用需求，并能够解决现有硅基片上光谱仪对温度敏感的问题。
上述内容即是本发明，硅基片上傅里叶变换光谱仪芯片的具体实施方案，同领域的科研或产业部门人员容易理解。以上内容仅为本发明的较佳实施例而已，并不用以限制本发明，凡在本发明的精神和原则之内所作的任何修改、等同替换和改进等，均应包含在本发明的保护范围之内。

Claims (8)

  1. 一种基于双层螺旋波导的片上傅里叶变换光谱仪，其特征在于，包括波导输入耦合器(1001)、1×N光分束器(1002)、N个双层波导Y分叉结构(1003)、N个双层螺旋波导(1004)、N个反向放置的双层波导Y分叉结构(1005)和N个锗硅探测器(1006)；
    所述的波导输入耦合器(1001)的输出端与所述的1×N光分束器(1002)的输入端相连，该1×N光分束器(1002)的N个输出端分别与所述的N个双层波导Y分叉结构(1003)的一个输入端相连，所述的N个双层波导Y分叉结构(1003)的输出端与所述的N个双层螺旋波导(1004)的输入端相连，所述的N个双层螺旋波导(1004)的输出端与N个反向放置的双层波导Y分叉结构(1005)的输入端相连，所述的N个反向放置的双层波导Y分叉结构(1005)的一个输出端与所述的N个锗硅探测器(1006)的输入端相连；
    所述的N个双层螺旋波导(1004)由N个长度线性递增的双层螺旋波导(3001)构成，每个双层螺旋波导的两层波导相互平行，且每个双层螺旋波导的宽度和高度与相对应的双层波导Y分叉结构的宽度和高度一致，所述的双层螺旋波导具有不同的群折射律的偶模和奇模，使得输出端有不同的光程差OPD i＝L i(n gO-n ge)，n go与n ge分别为奇模、偶模激励在双层螺旋波导中的群折射系数，L i为第i个双层螺旋波导长度。
  2. 如权利要求1所述的基于双层螺旋波导的片上傅里叶变换光谱仪，其特征在于，所述的波导输入耦合器(1001)、1×N光分束器(1002)、N个双层波导Y分叉结构(1003)、N个双层螺旋波导(1004)、N个反向放置的双层波导Y分叉结构(1005)和N个锗硅探测器(1006)集成在绝缘体上硅材料中，波导采用氮化硅材料。
  3. 如权利要求1所述的基于双层螺旋波导的片上傅里叶变换光谱仪，其特征在于，所述波导输入耦合器(1001)采用端面耦合器结构或光栅耦合器结构，待测光谱信号通过光纤耦合输入芯片中。
  4. 如权利要求1所述的基于双层螺旋波导的片上傅里叶变换光谱仪，其特征在于，所述的1×N光分束器(1002)实现入射光功率均分，采用log 2N级的级联1×2分束器结构，或者采用1×N多模干涉器结构。
  5. 如权利要求4所述的基于双层螺旋波导的片上傅里叶变换光谱仪，其特征在于，所述的1×2分束器结构为Y分叉、定向耦合器或多模干涉器(MMI)结构。
  6. 如权利要求1所述的基于双层螺旋波导的片上傅里叶变换光谱仪，其特征在 于，所述的N个双层波导Y分叉结构(1003)和N个反向放置的双层波导Y分叉结构(1005)都由N个相同结构的双层波导Y分叉结构(2001)构成，该Y分叉结构(2001)在合束处由上下两个宽度相同、厚度相同且相互平行的波导构成，即双层波导共同构成了合束端(2002)；在分叉处上下两个垂直波导在水平方向逐渐分开，各自成为单层波导(2003,2004)，实现入射光的分光以及波导从双层到单层的转换。
  7. 如权利要求1所述的基于双层螺旋波导的片上傅里叶变换光谱仪，其特征在于，所述的N个锗硅探测器(1006)采用锗硅PIN结构，将光功率信号转换为电信号。
  8. 如权利要求1至7任一项所述的基于双层螺旋波导的片上傅里叶变换光谱仪，其特征在于，所述的N个双层波导Y分叉结构(1003)、N个长度递增的双层螺旋波导(1004)和N个反向放置的双层波导Y分叉结构(1005)构成了类似具有递增光程差的非等臂马赫-增德尔干涉器阵列结构，实现空间外差相干的傅里叶变换光谱仪功能，双层螺旋波导阵列构成产生不同光程差的波导结构，光程差变化根据双层螺旋波导结构阵列中单个波导的螺旋长度变化。
PCT/CN2021/123482 2021-07-15 2021-10-13 基于双层螺旋波导的片上傅里叶变换光谱仪 WO2023284143A1 (zh)

Priority Applications (1)

Application Number Priority Date Filing Date Title
US18/413,015 US20240337536A1 (en) 2021-07-15 2024-01-15 On-chip fourier transform spectrometer based on double-layer helical waveguide

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CN202110801046.3A CN113640220B (zh) 2021-07-15 2021-07-15 基于双层螺旋波导的片上傅里叶变换光谱仪
CN202110801046.3 2021-07-15

Related Child Applications (1)

Application Number Title Priority Date Filing Date
US18/413,015 Continuation US20240337536A1 (en) 2021-07-15 2024-01-15 On-chip fourier transform spectrometer based on double-layer helical waveguide

Publications (1)

Publication Number Publication Date
WO2023284143A1 true WO2023284143A1 (zh) 2023-01-19

Family

ID=78417412

Family Applications (1)

Application Number Title Priority Date Filing Date
PCT/CN2021/123482 WO2023284143A1 (zh) 2021-07-15 2021-10-13 基于双层螺旋波导的片上傅里叶变换光谱仪

Country Status (3)

Country Link
US (1) US20240337536A1 (zh)
CN (1) CN113640220B (zh)
WO (1) WO2023284143A1 (zh)

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN114265150B (zh) * 2021-12-16 2022-09-06 浙江大学 一种支持片上远距离低损耗传输的紧凑线圈光波导
CN114371128B (zh) * 2022-01-13 2023-03-24 挚感(苏州)光子科技有限公司 一种基于多层平板波导结构的傅里叶变换光谱仪
CN115508958B (zh) * 2022-10-08 2024-05-24 深圳中科天鹰科技有限公司 一种基于光学神经网络的光子芯片

Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20120050744A1 (en) * 2010-07-28 2012-03-01 Gunma University Planar lightwave fourier-transform spectrometer measurement including phase shifting for error correction
CN102395866A (zh) * 2009-02-24 2012-03-28 艾迪株式会社 平面光波导傅里叶变换光谱仪
JP2017111062A (ja) * 2015-12-18 2017-06-22 キヤノン株式会社 光干渉断層計
CN110044484A (zh) * 2019-05-06 2019-07-23 长春理工大学 一种级联双环增强的傅里叶变换光谱仪
CN112013959A (zh) * 2020-09-08 2020-12-01 浙江大学 一种高分辨率大测量范围的硅基片上傅里叶变换光谱仪
CN112857570A (zh) * 2021-04-23 2021-05-28 中国电子科技集团公司信息科学研究院 一种硅基波导分光芯片及光谱分析系统

Family Cites Families (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN101477225B (zh) * 2009-01-19 2010-12-08 北京航空航天大学 光学波导及其制作方法与微光学陀螺
EP3182078A1 (en) * 2015-12-17 2017-06-21 IMEC vzw Stationary wave integrated fts with broadband operation
CN111624449B (zh) * 2020-05-28 2022-09-09 中国科学院电工研究所 一种基于发射光谱法的电力设备局部放电多通道光学检测系统

Patent Citations (6)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN102395866A (zh) * 2009-02-24 2012-03-28 艾迪株式会社 平面光波导傅里叶变换光谱仪
US20120050744A1 (en) * 2010-07-28 2012-03-01 Gunma University Planar lightwave fourier-transform spectrometer measurement including phase shifting for error correction
JP2017111062A (ja) * 2015-12-18 2017-06-22 キヤノン株式会社 光干渉断層計
CN110044484A (zh) * 2019-05-06 2019-07-23 长春理工大学 一种级联双环增强的傅里叶变换光谱仪
CN112013959A (zh) * 2020-09-08 2020-12-01 浙江大学 一种高分辨率大测量范围的硅基片上傅里叶变换光谱仪
CN112857570A (zh) * 2021-04-23 2021-05-28 中国电子科技集团公司信息科学研究院 一种硅基波导分光芯片及光谱分析系统

Also Published As

Publication number Publication date
US20240337536A1 (en) 2024-10-10
CN113640220B (zh) 2022-12-06
CN113640220A (zh) 2021-11-12

Similar Documents

Publication Publication Date Title
WO2022021880A1 (zh) 硅基片上傅里叶变换光谱仪及光谱重构方法
WO2023284143A1 (zh) 基于双层螺旋波导的片上傅里叶变换光谱仪
Nedeljkovic et al. Mid-infrared silicon-on-insulator Fourier-transform spectrometer chip
Bock et al. Subwavelength grating Fourier‐transform interferometer array in silicon‐on‐insulator
Wang et al. Photonic crystal self-collimation sensor
US10914634B2 (en) High-resolution integrated-optics-based spectrometer
Zhu et al. Self-assembled highly sensitive hybrid structure sensor for vector curvature and temperature measurement
Zhang et al. High-sensitivity refractive index sensor with cascaded dual-core photonic crystal fiber based on vernier effect
Alonso-Murias et al. Hybrid optical fiber Fabry-Perot interferometer for nano-displacement sensing
Chen et al. On-chip micro-ring resonator array spectrum detection system based on convex optimization algorithm
Sahu et al. Michelson interferometer based refractive index biosensor
Zhai et al. Study on high sensitivity measurement of seawater temperature based on bow tie fiber
Thomas et al. Expanding sampling in a SWIFTS-Lippmann spectrometer using an electro-optic Mach-Zehnder modulator
Resen et al. High sensitive temperature sensor based on narrow band-pass filters via optical heterodyne technique
Zhao et al. Sensitivity-enhanced temperature sensor by cascaded configuration of polarization mode interferometer and Lyot filter based on Vernier effect
Liu et al. Fiber temperature sensor based on Fabry-Pérot cavity generating optical Vernier effect
Lallement et al. Photonic beam-combiner for visible interferometry with Subaru coronagraphic extreme adaptive optics/fibered imager for a single telescope: laboratory characterization and design optimization
Dingel et al. Thin film-based Gires–Tournois Resonator (GTR) as quasi-optical analogue of the Thomas rotation angle effect in special relativity
Al-Saeed et al. Spot size effects in miniaturized moving-optical-wedge interferometer
Ai Multimode laser Fizeau interferometer for measuring the surface of a thin transparent plate
Li et al. Performance analysis of PLC-based 32-channel arrayed waveguide grating used for FBG interrogator
Chen et al. Sensitivity-enhanced optical sensor based on multilayer coated Fabry–Pérot interferometer
US11761750B1 (en) Multi-environment Rayleigh interferometer
Bru et al. Advanced integrated testing engine towards a complete characterization of photonic integrated devices
Mokeddem et al. Deep-learning algorithms for imperfection-resilient Fourier-transform spectroscopy in silicon

Legal Events

Date Code Title Description
121 Ep: the epo has been informed by wipo that ep was designated in this application

Ref document number: 21949916

Country of ref document: EP

Kind code of ref document: A1

NENP Non-entry into the national phase

Ref country code: DE

122 Ep: pct application non-entry in european phase

Ref document number: 21949916

Country of ref document: EP

Kind code of ref document: A1