Temperature sensitivity of the inline interferometer based on a two-core photonic crystal fiber selectively filled with polymer

We propose and demonstrate a highly sensitive micro-fluidic temperature sensor based on a two-core photonic crystal fiber (TCPCF). TCPCF has two cores of small asymmetry in sizes that serves as two arms in the inline Mach-Zehnder interferometer (MZI). Using manual gluing and subsequent infiltration technique, the cladding air holes near one core are selectively filled with polymer of high thermo-optic coefficient, which makes its core-mode effective index sensitive to temperature variation and induces large thermo-optic mismatch between the two cores. A high sensitivity of 1.595 nm/ oC is achieved in our experiment, which is almost 200 times improved from that of the sensor device before polymer infiltration process.