Ultrasensitive SPR-refractometer based on irregular metal-dielectric optical waveguide
A novel type of surface plasmon resonance (SPR) - based refractometer built around a bent single mode optical fiber with metalized cladding is studied numerically. Strong coupling between the fundamental and surface plasmon modes is shown to occur through the meditation of cladding modes at certain combinations of fiber bend radius and metal film thickness. This effect is demonstrated to enable precision refractive index measurement both in spectral and intensity-modulated modes with a resolution down to 10 <sup>-8</sup>.