Advanced optical terahertz fingerprint sensor based on coherent perfect absorption

Abstract

An advanced optical terahertz (THz) fingerprint sensor based on coherent perfect absorption (CPA) is proposed. Based on a one-dimensional layered photonic structure, the sensor contains a cavity that is developed for THz fingerprint measurement. Utilizing the magneto-optical effect of magnetized InSb, CPA is excited in the structure of the sensor. Taking α-lactose as exemplar material, this numerical simulation is integrated with a Drude–Lorentz model. The transfer matrix method (TMM) is used to calculate the sensitivity (S), linear range (LR), quality (Q), the figure of merit (FOM*), and detection limit (DL) theoretically. Employing the amplitude modulation detection method, the qualitative and quantitative analysis of the α-lactose thickness of 0–0.5 μm could be realized. Because of the fragility of CPA, the S is 0.78255 μm⁻¹, the value of average Q is up to 8019.2, the value of average FOM* is 13 234.4 (THz μm)⁻¹, and the lower DL is 4.21 × 10⁻⁶. Moreover, the evolutions of ensemble-averaged absorption in the vicinity of the absorption peaks for different types of disorder effects are considered, which will be considered in the fabrication of sensors.