Single-Material, Near-Infrared Selective Absorber Based on Refractive Index-Tunable Tamm Plasmon Structure

Abstract

As a powerful planar plasmonics, Tamm plasmon (TP) structures open up new possibilities for high-efficiency photonic applications demanding high quality (Q)-factor with scalability and spectral tunability. Despite the theoretical advantages of TP structures, TP configurations alternately stacked within limited materials and integer ranges result in thicker device sizes and still struggle to achieve ideal designs. Here, by introducing a computational model with varying design parameters, the configurations of high-performance TPs are presented within thin scale. However, the optimized configuration is hard to be realized with limited conventional materials. In this study, the effective refractive index is tailored through porosity change to achieve optimized design parameters, resulting in high Q-factors (approximate to 45) and near-unity absorptance (approximate to 99%) for sub-micron scale TPs (approximate to 0.7 mu m) based on single material. To verify single-material TPs (SMTPs), the real and imaginary parts of the optical impedances are calculated, which are well matching each other, resulting in unity absorption. Using the designed structure, SMTPs are experimentally fabricated based on glancing angle deposition. As a practical demonstration, SMTPs are combined with a metal-semiconductor-metal photodetector as an ultra-sensitive narrowband photodetector.