-
为了理解这种片上集成式光谱成像器件的物理机制,以13 μm的波段为例,计算了其电场分布,如图5所示。可以发现:与FP共振类似,下方的多层高反膜中几乎没有出现明显的电场增强的现象;光栅层中则出现了类似GMR的强局域的电场增强;而间隔层中的场分布虽然与FP共振相似,但是受到了光栅层中强局域的电场的影响,产生了一些波动,不再呈现出均匀分布的特征。因此,可以这样理解窄带透射峰的物理机制:1-D光栅和多层高反膜构成了一种类FP腔结构,该结构在满足振幅与相位匹配时会出现光学隧穿现象,从而激发透射峰。而微结构的引入导致了电场既无法完全局域于间隔层中,也无法像OTS一样以倏逝场的形式分布在分界面上,这种特殊的场分布情况表明了透射峰是上层光栅所激发的GMR与间隔层中的类FP共振共同耦合后的结果。
图 5 偏振光谱成像器件在13 μm处的电场分布
Figure 5. The electric field distribution of polarization spectral imaging device at 13 μm
对设计的大气红外的6个通道的透射光谱进行了计算,结果如图6所示。可以发现:各通道在满足高透射率的同时保持了非常低平的截止带(平均低于5%),6个通道的平均透过率和消光比分别达到了94%和30。各通道透射峰的具体光谱信息如透过率、线宽、消光比等和对应的结构参数参见表1。需要注意的是,图中TM偏振(即电场方向垂直于光栅刻槽方向)下,各通道均具有较低的透过率和较高的消光比,这一点凸显了该器件具有的偏振选择特性。
图 6 偏振光谱成像器件各通道在不同偏振下的透射光谱图
Figure 6. Transmission spectra of various channels of polarization spectral imaging devices under different polarizations
表 1 偏振光谱成像器件各通道对应的结构参数与光谱性能
Table 1. Structural parameters and spectral performance of polarization spectral imaging devices corresponding to each channel
Parameters and performance Channel/μm 12 12.5 13 13.5 14 14.5 Structural
parametersP/μm 10.52 11.1 12.44 12.86 11.6 11.27 F 0.12 0.18 0.19 0.29 0.57 0.66 Spectral
performanceLinewidth/nm 52 40 23 22 23 19 Peak transmittance TE 95.22% 97.43% 99.02% 96.59% 95.80% 80.89% TM 8.31% 7.06% 3.37% 2.20% 1.94% 2.25% Extinction ratio 11.46 13.80 29.38 43.90 49.38 35.95 从上述的设计结果可以发现:通过满足OTS的两个必要匹配条件,可以在一定范围内得到高透过率与消光比的片上集成式偏振光谱成像器件。然而,由于1-D光栅的横向参数所具有的调控自由度较少,且其提供的反射带宽也相对较窄,因此该器件的调控范围和调控能力还比较有限。如在14.5 μm处,由于相位和振幅的匹配情况不佳,尤其是此通道下的光栅层反射率已下降至70%以下,因此造成了透过率的明显下降(接近80%,远低于13 μm通道的99%);而短波处,TM偏振光谱中的透过率起伏则会导致短波处的消光比减小。此外,各通道的线宽调控机制,目前还不是非常清楚,如何使各通道线宽均匀分布,也是未来需要解决的重要问题。尽管如此,该工作依然为集成式偏振光谱成像器件的设计提供了新思路,随着上层微结构的复杂化例如引入拓扑超光栅、超表面[29−30]等,以及加强对多层高反膜的优化,未来有望实现更大的反射带宽和更强的相位调控能力,进而增强该器件的性能并增加其调控范围。
On-chip integrated polarization spectral imaging device for atmospheric infrared band
-
摘要: 红外探测与遥感是气象观测的核心技术,红外辐射探测仪作为气象卫星的重要载荷,主要用于大气温度、湿度的定量化探测,其探测精度取决于光谱和偏振测量的通道数。常见的技术方案是通过组合滤光片与偏振片转轮实现光谱和偏振的探测,这造成了系统体积大、功耗高、通道数少的问题。发展片上集成式偏振光谱成像器件是解决上述问题的有效方法,已有研究主要采用薄膜谐振腔或共振微结构的阵列化方案,但二者都无法兼顾光谱和偏振选择的要求。有鉴于此,提出了一种基于薄膜微结构耦合调控的设计新思路,以13 μm附近的大气红外波段为例,实现了片上集成式的偏振光谱成像,6个通道的平均透过率和消光比分别达到了94%和30。该器件有望在将来被广泛应用于偏振光谱成像领域中,同时,由于该器件对基底折射率并不敏感,基底的选择也会更加自由。Abstract:
Objective Infrared detection and remote sensing are the core technologies of meteorological observation. As an important payload of meteorological satellites, infrared radiation detectors are mainly used for quantitative detection of atmospheric temperature and humidity. Their detection accuracy depends on the number of spectral and polarization measurement channels. The common technical solution is to achieve spectral and polarization detection by combining filters and polarizer wheels, which leads to problems such as large system volume, high power consumption, and few channels. The development of on-chip integrated polarization spectral imaging devices is an effective method to solve the above problems. Previous studies have mainly used arraying schemes of thin film resonant cavities or resonant microstructures, but both cannot meet the requirements of spectrum and polarization selection. To solve these problems, this article proposes a new design approach based on coupling regulation of thin film microstructures, which can provide an on-chip integrated polarization spectral imaging device. Methods An on-chip integrated polarization spectral imaging device based on thin film microstructure, which combines a subwavelength grating broadband reflector and a multi-layer high reflection film is built in this paper (Fig.1). By constructing matching conditions for phase and amplitude at the interface between multilayer films and microstructures, narrow band transmission peaks with polarization selective characteristics can be excited through the coupling of them (Fig.2). Specifically, firstly one can design a broadband high reflectivity microstructure with a central wavelength of λ0, then design a high reflection film stack centered on λ0, with the outermost layer being a low refractive index interlayer, next adjust the appropriate spacing layer thickness Dspacer to make a narrow band transmission peak appears near the center λ0, last scan the transmission spectrum with changes in scanning period and duty cycle, find the parameter combination corresponding to the peak, and achieve multi-channel design (Fig.3). Meanwhile, by changing the lateral parameters of the microstructure, multi-channel polarization filtering can be achieved at different wavelengths, thus enabling on-chip integrated spectral imaging (Fig.4). Results and Discussions Taking the atmospheric infrared band around 13 μm as an example, an on-chip integrated polarization spectral imaging device with 6 channels is designed, the average transmittance of them is over 94% and the extinction ratio is about 30 (Fig.6 , Tab.1). In addition, research and exploration on the physical mechanisms (Fig.5) and fabrication schemes of the devices (Fig.7) are also conducted. Meanwhile, as the device is not sensitive to the refractive index of the substrate, the selection of the substrate could also be more flexible. This new design approach has opened up new doors for on-chip integrated spectral imaging devices. With the improvement of fabrication technology and further optimization of structure, it is expected to achieve better performance and be successfully applied in the field of polarization spectral imaging. In addition, in recent years, some low dimensional infrared detection materials such as GaSb nanowires have also shown excellent infrared detection performance, and due to their dimensional advantages, they can achieve the detection of polarized infrared light. Assigning spectral selection function to infrared detection materials with polarization selective properties will also be a new research approach in the future. -
图 3 (a) 1-D光栅在13 μm处的反射光谱;(b) 多层高反膜的反射光谱;(c) 多层高反膜在13 μm处随Dspacer变化的反射相位;(d) 偏振光谱成像器件在13 μm处的透射光谱
Figure 3. (a) The reflection spectrum of 1-D grating at 13 μm; (b) The reflection spectrum of multi-layer high reflection films; (c) The reflection phase spectrum of multi-layer high reflection films at 13 μm with the change of Dspacer; (d) The transmission spectrum of polarization spectral imaging device at 13 μm
表 1 偏振光谱成像器件各通道对应的结构参数与光谱性能
Table 1. Structural parameters and spectral performance of polarization spectral imaging devices corresponding to each channel
Parameters and performance Channel/μm 12 12.5 13 13.5 14 14.5 Structural
parametersP/μm 10.52 11.1 12.44 12.86 11.6 11.27 F 0.12 0.18 0.19 0.29 0.57 0.66 Spectral
performanceLinewidth/nm 52 40 23 22 23 19 Peak transmittance TE 95.22% 97.43% 99.02% 96.59% 95.80% 80.89% TM 8.31% 7.06% 3.37% 2.20% 1.94% 2.25% Extinction ratio 11.46 13.80 29.38 43.90 49.38 35.95 -
[1] Smith W L, Hilleary D T, Fischer J C, et al. Nimbus-5 ITPR experiment [J]. Appl Opt, 1974, 13(3): 499. doi: 10.1364/AO.13.000499 [2] Chalfant M W, Allegrino A S. Advanced TOVS (ATOVS) experimental cloud products using HIRS/3 and AMSU-A measurements [C]//Technical Proceedings of the 11th International TOVS Study Conference, Budapest, Hungary, 2000: 20-26. [3] Chen R, Gao C, Wu X, et al. Application of FY-4 atmospheric vertical sounder in weather forecast [J]. Journal of Infrared and Millimeter Wave, 2019, 38(3): 285-289. (in Chinese) [4] Tu H, Li H, Liu Q, et al. Estimation and evaluation of the land surface temperature from FengYun-3 series satellite data in northwest China [C]//2021 IEEE International Geoscience and Remote Sensing Symposium IGARSS, IEEE, 2021: 3729-3732. [5] Zhou X, Ni X, Zhang J, et al. A novel detection performance modular evaluation metric of space-based infrared system [J]. Optical and Quantum Electronics, 2022, 54(5): 274. doi: 10.1007/s11082-022-03622-x [6] Rodgers C D. Retrieval of atmospheric temperature and composition from remote measurements of thermal radiation [J]. Reviews of Geophysics, 1976, 14(4): 609-624. doi: 10.1029/RG014i004p00609 [7] Takizawa R, Kasai K, Kawakubo Y, et al. Reduced frontopolar activation during verbal fluency task in schizophrenia: a multi-channel near-infrared spectroscopy study [J]. Schizophrenia Research, 2008, 99(1-3): 250-262. doi: 10.1016/j.schres.2007.10.025 [8] Wang M. Atmosphere temperature profile sounder, ATPS-I [J]. Chinese Journal of Infrared Research, 1987, 6(1): 15-20. (in Chinese) [9] Zhang Z, Wang M. Atmospheric sounding infrared spectroradiometer Type II [J]. Journal of Infrared and Millimeter Wave, 1992, 11(4): 265-270. (in Chinese) [10] Nolin A W. Recent advances in remote sensing of seasonal snow [J]. Journal of Glaciology, 2010, 56(200): 1141-1150. doi: 10.3189/002214311796406077 [11] Sun X, Qiao Y, Hong J. Review of research progress and related applications of visible and infrared polarization remote sensing technology [J]. Journal of Atmospheric and Environmental Optics, 2010, 5(3): 175-189. (in Chinese) [12] Xie K, Wang M, Yin D. Research progress of infrared spectrometer technology for atmospheric detection [J]. Infrared, 2003, (02): 33-36. (in Chinese) [13] Wang Q, Shen H, Liu W, et al. Design of compact mid-infrared cooled echelle spectrometer based on toroidal uniform-line-spaced (TULS) grating [J]. Sensors, 2022, 22(19): 7291. doi: 10.3390/s22197291 [14] Koenig E W. Performance of the HIRS/2 instrument on TIROS-N [J]. Remote Sensing of Atmospheres and Oceans , 1980: 67-91. [15] Deschamps P Y, Bréon F M, Leroy M, et al. The POLDER mission: Instrument characteristics and scientific objectives [J]. IEEE Transactions on Geoscience and Remote Sensing, 1994, 32(3): 598-615. doi: 10.1109/36.297978 [16] Persons C M, Chenault D B, Jones M W, et al. Automated registration of polarimetric imagery using Fourier transform techniques [C]//Polarization Measurement, Analysis, and Applications V, SPIE, 2002, 4819: 107-117. [17] Saxe S, Sun L, Smith V, et al. Advances in miniaturized spectral sensors [C]//Next-Generation Spectroscopic Technologies XI, SPIE, 2018, 10657: 69-81. [18] Gonzalez P, Geelen B, Blanch C, et al. A CMOS-compatible, monolithically integrated snapshot-mosaic multispectral imager [J]. NIR News, 2015, 26(4): 6-11. doi: 10.1255/nirn.1531 [19] Mamun M A, Sayeed R M, Gigante M, et al. Dual-period guided-mode resonance filters for SWIR multi-spectral image sensors [J]. Optics Letters, 2021, 46(9): 2240-2243. doi: 10.1364/OL.424772 [20] Sayeed R M, Mamun M A, Avrutin V, et al. Pixel-scale miniaturization of guided mode resonance transmission filters in short wave infrared [J]. Optics Express, 2022, 30(8): 12204-12214. doi: 10.1364/OE.449628 [21] Li Zhifeng, Li Qian, Jing Youliang, et al. Plasmonic microcavity coupled high extinction ratio polarimetric long wavelength quantum well infrared photodetectors(Invited) [J]. Infrared and Laser Engineering, 2021, 50(1): 20211006. (in Chinese) doi: 10.3788/IRLA20211006 [22] Xia Lipeng, Liu Yuheng, Zhou Peiji, et al. Advances in mid-infrared integrated photonic sensing system (Invited) [J]. Infrared and Laser Engineering, 2022, 51(3): 20220104. (in Chinese) doi: 10.3788/IRLA20220104 [23] Goto T, Dorofeenko A V, Merzlikin A M, et al. Optical Tamm states in one-dimensional magnetophotonic structures [J]. Physical Review Letters, 2008, 101(11): 113902. doi: 10.1103/PhysRevLett.101.113902 [24] Treshin I V, Klimov V V, Melentiev P N, et al. Optical Tamm state and extraordinary light transmission through a nanoaperture [J]. Physical Review A, 2013, 88(2): 023832. doi: 10.1103/PhysRevA.88.023832 [25] Wu J, Wu F, Zhao T, et al. Dual-band nonreciprocal thermal radiation by coupling optical Tamm states in magnetophotonic multilayers [J]. International Journal of Thermal Sciences, 2022, 175: 107457. doi: 10.1016/j.ijthermalsci.2022.107457 [26] Zheng J, Han P, Chen Y. Study of surface states of single negative metamaterials [J]. Semiconductor Optoelectronics, 2013, 34(5): 815-819. (in Chinese) [27] Yan P. Research on Q-value enhancement of resonant cavity with resonant optical tunneling effect[D]. Taiyuan: Taiyuan University of Technology, 2021. (in Chinese) [28] Juha M K, Janne S, Kari L, et al. Broadband infrared mirror using guided-mode resonance in a subwavelength germanium grating [J]. Optics Letters, 2010, 35(15): 2564-2566. doi: 10.1364/OL.35.002564 [29] Jiang J, Sell D, Hoyer S, et al. Free-form diffractive metagrating design based on generative adversarial networks [J]. ACS nano, 2019, 13(8): 8872-8878. doi: 10.1021/acsnano.9b02371 [30] You J W, Lan Z, Ma Q, et al. Topological metasurface: From passive toward active and beyond [J]. Photonics Research, 2023, 11(3): B65-B102. doi: 10.1364/PRJ.471905 [31] Liu F, Jiao H, Zhang J, et al. High performance ZnS antireflection sub-wavelength structures with HfO2 protective film for infrared optical windows [J]. Optics Express, 2021, 29(20): 31058-31067. doi: 10.1364/OE.439405