提出了一种基于法布里-珀罗腔的二维光子晶体温控光衰减器,此结构利用掺杂硅的热光效应对光子晶体折射率进行线性调制,折射率的变化引起了光子晶体的带隙以及法布里-珀罗腔光程差的变化,并导致反射率在某一温度区间内随温度线性变化,实现了对入射光的可控衰减。利用商业电磁仿真软件CST模拟了含掺杂硅的基于法布里-珀罗腔的光子晶体反射率光谱曲线,该曲线随温度发生平移;并仿真了此结构在特定频率下,其反射率随温度变化的规律,在频率为0.284 THz时,曲线具有较好的线性度;仿真了4种不同的入射角情况,并对入射角为3°的温度-反射率曲线进行了线性拟合,得出了表征公式。最终设计出了一款调谐幅度为0~7.68%的光子晶体温控光衰减器。

A two-dimensional photonic crystal optical attenuator with temperature control based on the Fabry-Pérot cavity is proposed. The structure utilizes the linear modulation of the refractive index of the photonic crystal induced by thermooptic effect of the doped silicon. The change in refractive index causes variations in the photonic crystal bandgap and optical path difference of the Fabry-Pérot cavity. This causes linear variation in reflectivity as a function of temperature within a specific temperature domain, which realizes the controllable attenuation of the incident light. A commercial electromagnetic simulation software, CST, is used to simulate the reflectance spectrum of the photonic crystal with the Fabry-Pérot cavity after silicon doping, showing that the spectrum curve shifts as a function of temperature. The variation pattern of reflectivity is simulated for this structure as a function of temperature at several specific frequencies. It is found that the curve has relatively good linearity at a frequency of 0.284 THz. The simulation is conducted for incidence angles of 1°, 3°, 5°, and 8°, respectively, whereas the linear fitting is performed for the temperature-reflectivity curve at 3°, through which the characterization formula is obtained. A temperature-controlled photonic crystal optical attenuator with a tuning amplitude of 0-7.68% is designed.