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 1100°C, good temperature sensitivity of 10.15 pm/°C and 16.92 pm/°C, within the temperature region between 100 and 400 °C, and between 400 and 1100 °C, 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.