Inline Mach-Zehnder Interferometer using Liquid Filled Twin-Core Photonic Crystal Fiber with High Strain Sensitivity

An inline Mach-Zehnder interferometer (MZI) is demonstrated using liquid filled twin-core photonic crystal fiber (TC-PCF). The TC-PCF is filled selectively with liquid ethanol, increasing the effective refractive index contrast between twin cores, resulting in interference fringe spectrum with narrower free spectral range (FSR). Strain induced wavelength shift of the interference fringes is experimentally monitored. Wavelength shifts to the shorter wavelength side with a sensitivity of about -1.48 pm/mu epsilon for applied strain change. Selectively liquid filled TC-PCF based MZI is simple to fabricate and expected to have wide range of applications in optical sensors, multi-wavelength laser source and tunable optical devices.