Hollow-core fiber sensor based on the long-range Tamm plasmon polariton with enhanced figure of merit

Abstract

The potential of long-rang Tamm plasmon polariton (LRTPP) for sensing applications is theoretically investigated in a planar distributed Bragg reflector (DBR) structure containing a thin metal film. Results show that both sensitivity and figure of merit (FOM) increase with increasing incidence angle under transverse electric polarization. Due to the difficulty of achieving very large incidence angles in planar structures in practice, a LRTPP based hollow-core fiber (HF) sensor is proposed, where all transmitted lights in the fiber core have large incidence angle close to 90° on the inner surface of the HF. The ray transmission model is adopted to calculate the transmission spectra of the proposed HF LRTPP sensor. A comprehensive theoretical analysis about the influence of the structural parameters on the sensor performance is carried out, including the thickness of the metal layer and the number of periods of the DBRs. The HF LRTPP sensor achieves a sensitivity of 774 nm/RIU and FOM of 227.6 RIU−1 at the refractive index (RI) around 1.00 for gas sensing. In the RI range of 1.33–1.53, a sensitivity of 705 nm/RIU and FOM of 201.4 RIU−1 are achieved. The FOM of the HF LRTPP sensor is 2–7 times higher than that of the HF Tamm plasmon polariton (TPP) sensor, while the sensitivities are comparable. Benefiting from the lower attenuation and narrower resonance dip, the idea of utilizing LRTPP mode in DBR-metal-DBR structure to improve the sensor performance will provide a new way for the design of TPP sensors and promote the related researches.

Keywords

• Tamm plasmon polariton
• Hollow-core fiber
• Refractive index sensor
• Optical fiber sensor