Mach-Zehnder interferometer in embedded-core optical fiber
A novel Mach-Zehnder interferometer (MZl) based on a pair of long period fiber gratings (LPGs) in an embedded-core hollow optical fiber (ECOF) are proposed and demonstrated experimentally. Two similar LPGs with peak attenuation of approximately 3dB are fabricated in an ECOF by using high-frequency CO2 laser to form an in-fiber MZI. The dependences of the resonant peak on the temperature and the axial strain were studied. Experimental results show that sensitivities of the temperature and the axial strain are 64.3 pm/°C and 0.4 pm/με, respectively.