基于等离激元效应的近红外偏振滤光片的模拟研究

Simulation Study of Near-Infrared Polarizing Filter Based on Plas-mon Effect

摘要: 本文基于表面等离子激元(Surface Plasmons, SPs)理论，结合有限时域差分法(Finite Difference Time Domain method, FDTD)对周期性亚波长金属光栅的偏振特性进行了模拟研究，并利用等效介质理论分析了亚波长光栅产生偏振的原因，深入分析入射波长在0.8~1.7 μm内，亚波长金属光栅的周期、占空比、厚度以及金属材料对透射光偏振特性的影响。结果表明Al和Au的共同之处是都可以对金属光栅产生偏振调控，不同之处是Al对于消光比的调控较明显、Au对于透过率的调控较明显。此外亚波长金属光栅的周期与透过率、消光比均成正比；占空比与透射率成正比，与消光比成反比；光栅厚度对消光比的影响较明显。本研究为偏振光谱成像芯片的核心部件近红外偏振滤光膜系的应用奠定了基础。

Abstract: Based on the theory of Surface Plasmons (SPs), this paper combines the Finite Difference Time Domain method (FDTD) to simulate the polarization characteristics of periodic sub-wavelength metal gratings, and uses the equivalent medium theory. Explain the reasons for the polarization of the sub-wavelength grating, and analyze in depth the influence of the period, duty cycle, thickness and metal materials of the sub-wavelength metal grating on the polarization characteristics of the transmitted light within the incident wavelength of 0.8~1.7 μm. The results show that the commonality of Al and Au is that both can control the polarization of the metal grating. The difference is that Al controls the extinction ratio more obviously, and Au controls the transmittance more obviously. In addition, the period of the sub-wavelength metal grating is directly proportional to the transmittance and extinction ratio; the duty cycle is directly proportional to the transmittance and inversely proportional to the extinction ratio; the thickness of the grating has a more obvious influence on the extinction ratio. This research lays the foundation for the application of the near-infrared polarization filter film, the core component of the polarization spectrum imaging chip.