Research On The Characteristic And Application Of The One-Dimensional Non-polarizing Guided-mode Resonance Grating

The pure-dielectric Guided-mode resonance (GMR) grating can be used as anoptical filter with good properties, which has been widely researched in recent years. Insome special applications such as the polarization of optical signals are unknown ornon-polarizing filtering applications are necessary, filters which are not sensitive to thepolarization of the incident wave are needed. Previously, two-dimensional gratings orone-dimensional multi-layer gratings under complicated incidence were used to achievenon-polarizing filters. This paper focuses on the one-dimensional single-layernon-polarizing GMR grating under normal incidence and reveals the feasibility that thismost simple grating can be used as a non-polarizing filter.Based on the approximate slab waveguide model, the fact that a single-layerone-dimensional GMR grating can exhibit polarization independent resonancecharacteristic is proved.For sinusoidal profile grating and Type I rectangular grating, the CoordinateTransformation Method and the Fourier Modal method are used to analyze the influenceof structural parameters on the location of the resonance wavelength and FWHM,respectively. Approximate relationships of the structure parameters are acquired whichcan be used to obtain the nonpolarizing GMR grating at850nm. By cooperation withthe Aalto University of Finland and the Tsinghua university-foxconnnanotechnology research center, Light-induced Polymer Deformation, AtomicLayer Deposition and Electron Beam Lithography are used to fabricate thegrating samples. Test results show that the sinusoidal profile grating can realizethe nonpolarizing GMR effect at900nm, approximately. The resonance peakdeviation between TE and TM is about15nm. For Type I rectangular grating, theresonance peaks of TE and TM almost both locate at840nm with only2.4nmdeviation. The FWHM of TE resonance is30nm, while FWHM of TM is38nm.The resonance characteristics of theoretical and experimental results match eachother very well. In order to prove the universality of nonpolarizing resonancewavelength, structural parameters of nonpolarizing Type I rectangular GMRgrating are designed at resonant wavelengths532nm,633nm,633nm,1300nm and1550nm. In addition, by calculating the dispersion curve of guided mode in grating, the physical mechanism for grating realizing the nonpolarizing GMR effect isshowed.Because Type II rectangular grating is easier to achieve large-scale production,grating structure is designed to achieve nonpolarizing resonance at850nm. Bycooperation with the University of Eastern Finland, the grating sample is fabricated byuse of Electron Beam Lithography, Nanoimprint technology and Atomic LayerDeposition. Test results show that the resonance peaks of TE and TM both locate at840nm with a1.4nm difference, showing a very good nonpolarizing resonancecharacteristic. But the FWHM of the two polarizations are quite different, and thesidelobe cannot get a very good suppression.In order to improve the filtering performance of the unpolarizing GMR grating, thenonpolarizing reflection and transmission type GMR grating filters are designed at thewavelength850nm based on the hybrid structure of multilayer films and grating undernormal incidence. The sidelobe is controlled within10%, and FWHM is controlled inless than2nm.