Refractive-index-modified-dot Fabry-Perot fiber probe fabricated by femtosecond laser for high-temperature sensing.

An optical fiber Fabry-Perot probe sensor for high-temperature measurement is proposed and demonstrated, which is fabricated by inducing a refractive-index-modified-dot (RIMD) in the fiber core near the end of a standard single mode fiber (SMF) using a femtosecond laser. The RIMD and the SMF end faces form a Fabry-Perot interferometer (FPI) with a high-quality interference fringe visibility (>20dB). As a high-temperature sensor, such an FPI exhibits a sensitivity of 13.9pm/°C and 18.6pm/°C in the range of 100-500°Cand 500-1000°C,respectively. The fabrication process of this device is quite straightforward, simple, time saving, and the sensor features small size, ease of fabrication, low cost, assembly-free, good mechanical strength, and high linear sensitivity.