基于铌酸锂光折变光栅的表面等离子滤波器

Surface Plasma Filter Based on Photorefractive Grating in Lithium Niobate

基于铌酸锂光折变光栅和表面等离子共振(SPR)效应,设计了一种绝缘体-金属-绝缘体结构的滤波器,利用二维有限元法仿真得到,波长656 nm时SPR角度为46.399 5°。在定义了光折变复合折射率的基础上,理论推导了SPR波长对双光束半角的灵敏度。最后研究了铌酸锂晶体内不同光栅周期时,宽光谱光源固定入射激励SPR的光谱特性,发现反射光谱中满足SPR的波长被滤除;改变光折变光栅周期,SPR所激励的波长发生偏移。该器件有望用来实现可调谐滤波。

An insulator-metal-insulator filter based on Surface Plasmon Resonance（SPR） and photorefractive（PR） grating in Lithium niobate（LiNbO3） is designed. Through numerical simulation by using two-dimensional finite element method, incident angle of 46.399 5° for stimulating SPR was calculated at a fixed wavelength 656 nm. On the basis of definition of complex refractive index, sensitivity of SPR wavelength to half angle of dual beam was theoretically derived. Finally, under different grating periods in LiNbO3, reflection spectrum of SPR stimulated from a broadband light source was studied. The results show wavelengths corresponding to SPR are filtered and the SPR wavelengths shift when the period of PR grating is changed. The designed device is expectable for tunable filtering.