A novel CPA-based layered photonic structure for multipurpose sensing applications

Contrary to the traditional single-function sensor, a layered photonic structure (LPS) is proposed in this paper for multipurpose sensing based on the mechanism of coherent perfect absorption (CPA), which can simultaneously detect changes in the thickness of the dielectric layers, the refractive index, the incident angle, and the applied magnetic field intensity. Utilizing the Faraday effect of magnetized yttrium iron garnet, CPA is excited in the LPS. The transfer matrix method (TMM) is utilized to theoretically calculate the sensitivity, linear range, and figure of merit of the structures. To achieve high adaptability and a wide sensing range, the LPS provides two modulation detection methods based on CPA: phase modulation, which regulates and compensates for absorption via changing the optical phase, and frequency modulation, which utilizes the frequency band in comb-like absorption peaks. Due to the fragility of CPA, the multipurpose structure is of high precision, high-sensitivity. Furthermore, LPS benefits from its compact size and ease of fabrication. Therefore, we expect that our study will have some viable potential in the gauging arena.