Silica bottle resonator sensor for refractive index and temperature measurements

We propose and theoretically demonstrate a bottle resonator sensor with a nanoscale altitude and with alength several of hundreds of microns made on the top of the fiber with a radius of tens microns for refractive index and temperature sensor applications. The whispering gallery modes (WGMs) in the resonators can be excited with a taper fiber placed on the top of the resonator. These sensors can be considered as an alternative to fiber Bragg grating (FBG) sensors.The sensitivity of TM-polarized modes is higher than the sensitivity of the TE-polarized modes, but these values are comparable and both polarizations are suitable for sensor applications. The sensitivity similar to 150 (nm/RIU) can be reached with abottle resonator on the fiber with the radius 10 m. It can be improved with theuse of a fiber with a smaller radius. The temperature sensitivity is found to be similar to 10 pm/K. The temperature sensitivity can decrease similar to 10% for a fiber with a radius r(co) = 10 m instead of a fiber with a radius r(co) = 100 m. These sensors have sensitivities comparable to FBG sensors. A bottle resonator sensor with a nanoscale altitude made on the top of the fiber can be easily integrated in any fiber scheme.