基于多变量纳米线栅复合结构的可见光偏振调控

Polarization control of visible light based on composited multivariable nanowire gratings structure

偏振调控技术能够直接满足偏光显微镜在可见光波段快速、高精度识别检测的需求,其关键是,在提高偏振消光比的同时,具有较高的光利用率。基于等效介质理论和谐振腔的共振增强机理,设计了一种多变量纳米线栅复合结构;采用时域有限差分方法,通过数值仿真,分析了纳米线栅各结构参数和偏振调控的变化关系,能够实现可见光波段宽角度入射、高透过率和高消光比的偏振快速调控功能;结合实验室现有条件,采用纳米压印技术进行样品制备和实验验证。实验和仿真结果表明:在入射角度±35°内,TM模偏振光的透射率和消光比分别高于60%和35 dB;并且在532 nm激光源垂直入射时,TM模偏振光的透射率和消光比与仿真结果误差范围为4%。与现有偏振显微镜设备中偏振器相比,所设计的纳米线栅偏振调控在保证高透过率的同时,消光比提升了1.5倍。

The polarization regulation technology can effectively fulfill the requirements of rapid and precise identification and detection in the visible light range for polarization microscopes.The key lies in enhancing the polarization extinction ratio and achieving the optimal utilization of light.A composited multivariable nanowire gratings structure was designed based on the equivalent medium theory and the resonance enhancement mechanism of the resonator.The relationship between the structure parameters and polarization property of the structure was analyzed by numerical simulation using the finite-difference time-domain(FDTD)method,which could realize the polarization regulation function of wide angle incidence,high transmittance and high extinction ratio in the visible light band.Combined with the existing conditions of the laboratory,the nano-imprint technology was used for sample preparation and experimental verification.The experimental and simulation results show that the transmittance and extinction ratio of TM mode are higher than 60%and 35 dB respectively within the incident angle of±35°,and the error range is about 4%at the vertical incidence of 532 nm laser source.Compared with polarizers in existing polarization microscopes,the designed structure of polarization regulation ensures high transmittance while increasing the extinction ratio by 1.5 times.