Single microchannel high-temperature fiber sensor by femtosecond laser-induced water breakdown.

Single microchannel high-temperature fiber sensors were fabricated by drilling a microchannel across the fiber core near the end of the common single-mode fiber using femtosecond laser-induced water breakdown. Then the microchannel was annealed by the arc discharge to smooth its inwall. The two sides of microchannel and the end surface of the fiber constitute three reflective mirrors, which form a three-wave Fabry-Pérot interferometer (FPI). The fabricated FPI can be used as a high-temperature sensor in harsh environments due to its large temperature range (up to 1000°C), high linearity, miniaturized size, and perfect mechanical property.