Femtosecond Laser Inscribed Multiple In-Fiber Reflection Mirrors for High-Temperature Sensing

We propose and demonstrate a high-temperature sensing device based on multiple reflection mirrors inscribed in optical fiber by femtosecond laser. The output spectrum of the device has a number of dominant wavelength peaks with controllable spacing and bandwidth formed by adjusting the reflection mirror separation. The device has excellent high-temperature sustainability up to 1100C, good temperature sensitivity of 10.15pmC and 16.92pmC, within the temperature region between 100 and 400C, and between 400 and 1100C, respectively. The fiber device is simple in configuration, robust in structure, easy in fabrication and convenient in operation, and has high potential in sensing applications especially for high-temperature monitoring in harsh environment.