Compact Mach–Zehnder interferometer-based no-core fiber hollow-core fiber no-core fiber structure

We propose and experimentally demonstrate a compact Mach–Zehnder interferometer (MZI)-based no-core fiber hollow-core fiber no-core fiber (NHN) structure. Two segments of the no-core fiber embedded on two ends of the hollow-core fiber are employed as beam splitter and combiner, which realize an MZI to measure temperature and strain. With the variation of the temperature and strain, the measurement is achieved by monitoring the transmission spectrum shift of the MZI. The results show that the proposed sensor has a temperature sensitivity of 30.92 pm/°C in the range from 30°C to 90°C, and strain sensitivity of 0.652 pm/μϵ in the range from 0 to 700 μϵ, respectively. The NHN structure exhibits the advantages of compactness, easy fabrication, and low cost, which shows the potential sensing applications of the proposed fiber structure.