A fiber inline interferometric refractive index(RI) sensor consisting of a microchannel and a fiber taper is proposed in this letter. The microchannel is fabricated by combining femtosecond laser micromachining and arc fusion splicing. No subsequent chemical etching process is needed. Three sensors with microchannel widths of 4, 8, and 10 μm are prepared. The sensitivity in the RI range from 1.33 to 1.35 is up to～361.29 nm/RIU at the microchannel width of 8 μm. The sensitivity is ～20 times greater than that of the paired taper-based MZI sensors and long period fiber grating pair MZI sensors.
A high temperature sensor based on an ultra-abrupt tapered fiber Michelson interferometer fabricated by the fusion-splicing method is proposed. The sensor consists of a single abrupt taper and the cleaved surface is used as the reflection mirror. The thermal characteristic is investigated at 25 to 1 000℃. The sensitivity of the sensor is observed to vary with the temperature, that is, 25 and 78 pm/℃ at 25-300 and 300-1 000℃, respectively. The Michelson interferometer sensors have the advantages of simple structure, cost effectiveness, compactness, and simple fabrication process.
This study proposes a new hybrid Mach-Zehnder interferometric(MZI) sensor based on two core-offset attenuators and an abrupt taper in a single-mode fiber fabricated by a fiber-taper machine and electric arc discharge. When the distance between the two core-offset attenuators is stretched to 4500 μm, significant interference signals are detected with a prominent attenuation peak of ～28 dB. The proposed MZI can be used to measure temperature due to its low refractive index(RI) and strain cross-sensitivity. The temperature sensitivity is 34.95±0.04 and 106.70±0.04 pm/℃ in the temperature ranges of 14-250 and250-1000 ℃, respectively.
