Robust high temperature sensor probe based on a Ni-coated fiber Bragg grating

A robust high temperature sensor probe based on a Ni-coated fiber Bragg grating(FBG) was fabricated by Ni electroplating of femtosecond laser written FBG. The probe can resist high temperature up to 800 °C with a high sensitivity of 32.2 pm/°C. It also has a good mechanical strength even after high temperature annealing. The thermal strain of the probe was simulated by the finite element method(FEM). The Bragg resonant wavelength shift with temperature and its sensitivity change with the thickness of the Ni-coated layer were also calculated.