A Compact In-fiber MZI Based on Dual Side-hole Fiber

We present and demonstrate a compact Mach-Zehnder interferometer (MZI) based on a dual side-hole fiber (DSHF). The structure is fabricated by fusion splicing a short section of dual side-hole fiber in between two short pieces of multimode fibers. The responses of the MZI to multi parameters are measured through the wavelength shift of the interference spectrum caused by the light beams transmitting along two air holes and the core of the DSHF. The experimental results show that the temperature and strain responses of the MZI are 37.4 pm/ ºC in the range of 20 ºC – 100 ºC and 0.9 pm/με in the range of 0 με – 1040 με, respectively. In addition, the structure is insensitive to surrounding refractive index. The most valuable application of the proposed MZI is that it can be used as a high sensitive gas pressure senor by keeping one air hole closed and making the other one opened by drilling the DSHF with femtosecond laser.