Surface plasmon resonance in a metal-coated single-mode optical fiber with decreased normalized frequency

We have numerically simulated the excitation of surface plasmon resonance in a bent metal-coated single-mode optical fiber with decreased normalized frequency. It is established that an optimum combination of the normalized frequency, bending radius, and film thickness favors effective energy transfer from guided radiation to a plasmon-polariton wave excited on the surface of a metal film deposited onto the optical cladding. It is shown that, using this effect, it is possible to measure the refractive index (RI) of an external medium with a spectral sensitivity of 70 $\mu$m/RI unit and a resolution of up to 3 $\cdot$ 10$^{-7}$ RI unit.