Broadband and high-enhancement-factor integrated long-wave infrared sensor using the photonic crystal assisted subwavelength grating waveguide

Abstract

In this paper, a broadband and high-enhancement-factor integrated long-wave infrared sensor using the photonic crystal assisted subwavelength grating waveguide is presented, optimized, and analyzed in detail. By reasonably designing the structure and optimizing the corresponding parameters, the dispersion relationship can be adjusted to realize a relatively flat band and the slow-light effect can be introduced to improve the interaction between light and matter so that large and stable slow-light enhancement factors are obtained in a wide wavelength range, achieving high-performance detection of multiple types of matter. For the optimized sensor, the operating bandwidth from 7.65142 to 7.71125 µm is realized. When C2H2, HNO3, CH4, H2O2, or N2O is treated as the target matter, the corresponding slow-light enhancement factor at 7.677 µm, 7.661 µm, 7.670 µm, 7.7 µm, or 7.705 µm is, respectively, 4.3405, 4.3432, 4.3194, 5.1584, or 5.9745; the relevant sensitivity is 0.2394Wmol−1L, 0.3466Wmol−1L, 0.3639Wmol−1L, 0.2058Wmol−1L, or 0.4791Wmol−1L; and the minimum detectable concentration is 0.6032 ppb, 0.4164 ppb, 0.3966 ppb, 0.7019 ppb, or 0.3010 ppb.