Ultra-sensitive and wide-range temperature sensing utilizing a microbottle resonator coupled with fiber Mach-Zehnder interferometer

An ultra-sensitive and wide-range temperature detection method has been proposed based on coupling a microbottle resonator with a fiber Mach-Zehnder Interferometer (FMZI), which can change the small mode shift into a large intensity variation. We theoretically and experimentally investigated the sensing performance of this method. Through appropriately adjusting the length difference of FMZI, the microbottle resonant peaks and the FMZI peak move in opposite directions. Measuring the Fano dip depth gives a temperature sensitivity of up to 307.5 dB/°C and a temperature resolution of 4 × 10^-3 °C. Theoretical calculations demonstrate that the temperature detection limit can reach 4 × 10^-6 °C under an 80 dB Signal-to-Noise Ratio (SNR). Moreover, experiments have confirmed that by using the encoding method of universal commercial barcodes to record the changes in the resonant frequencies and intensities of the modes and by matching the proposed barcodes with the Bit Error Rate, temperature sensing with an almost unlimited range can be achieved. The proposed method makes it possible to achieve high sensitivity and a wide range of temperature sensing applications.