Ultra-high sensitivity temperature sensor based on PDMS-assisted-cascaded Mach–Zehnder Interferometer

In this paper, we propose and demonstrate an ultra-high sensitivity temperature sensor based on Polydimethylsiloxane (PDMS) assisted-cascaded Mach–Zehnder Interferometers (PAC-MZI). The sensor is first fabricated by periodically embedding four segments of hollow core fibers (HCF) in a single-mode fiber(SMF). Then, we drill holes into the sidewall of the HCF with a CO2 laser. Finally, the vacuum aspiration technique is used to introduce the PDMS into the HCF. In addition to serving as a beam splitter and combiner, the PDMS-filled HCF also guides multiple modes. The evolution of the transmission spectra during the fabrication process is thoroughly examined. The experimental temperature sensitivity of the sensor surpasses that of conventional interferometric temperature sensors by about 300 times to 9.53 nm/°C. Combining the advantages of easy packaging, compact structure, and high sensitivity, the proposed sensor has a wide range of potential applications in the field that require high-sensitivity temperature measurement.