We successfully fabricate and demonstrate a type of in-line M-Z interferometer by using single mode fiber and suspended dual-core hollow fiber. We fuse one section of dual-core hollow fiber (about 5-10cm length used as interferometer arms) with two part of single mode fiber by arc discharging on their cross sections. After this new M-Z interferometer’s fabrication and related experiments, we improved it by absorbing drops of alcohol in its dual-core hollow body which can do much of contributions to its sensitivity. With bunches of temperature experiments conducted, we find this new interferometer has a good temperature sensitivity highly as 1.751nm/°C (from 20 to 100 °C) and interferometer with alcohol inside has a better temperature sensitivity highly as 3.015nm/ °C (from 20 to 60 °C) respectively.
Long period fiber gratings (LPFGs), which can couple the core mode to the forward propagating cladding modes of a fiber and have the advantage of small additional loss, no backward reflection, small size, which is widely used in optical fiber sensors and optical communication systems. LPFG has different fabricating methods, in order to write gratings on the twin-core at the same time effectively, we specially choose electric heating fused taper system to fabricate asymmetric dual-core long period fiber grating, because this kind of method can guarantee the similarity of gratings on the twin cores and obtain good geometric parameters of LPFG, such as cycle, cone waist. Then we use bending test platform to conduct bending test for each of the core of twin-core asymmetric long period fiber grating. Experiments show that: the sensitivity of asymmetrical twin-core long period fiber grating’s central core under bending is -5.47nm·m, while the sensitivity of asymmetric twin-core long period fiber grating partial core changed with the relative position of screw micrometer. The sensitivity at 0°, 30°, 90° direction is -4.22nm·m, -9.84nm·m, -11.44nm·m respectively. The experiment results strongly demonstrate the properties of rim sensing of asymmetrical twin-core fiber gratings which provides the possibility of simultaneously measuring the bending magnitude and direction and solving the problem of cross sensing when multi-parameter measuring. In other words, we can detect temperature and bend at the same time by this sensor. As our knowledge, it is the first time simultaneously measuring bend and temperature using this structure of fiber sensors.