RESUMEN
A novel high-sensitivity temperature sensor based on a chirped thin-core fiber Bragg grating Fabry-Perot interferometer (CTFBG-FPI) and the Vernier effect is proposed and demonstrated. With femtosecond laser direct writing technology, two CTFBG-FPIs with different interferometric cavity lengths are inscribed inside a thin-core fiber to form a Vernier effect system. The two FPIs consist of two pairs of CTFBGs with a full width at half maximum (FWHM) of 66.5â nm staggered in parallel. The interferometric cavity lengths of the two FPIs were designed to be 2 mm and 1.98 mm as the reference arm and sensing arm of the sensor, respectively. The temperature sensitivity of this sensor was measured to be -1.084â nm/°C in a range of 40-90°C. This sensor is expected to play a crucial role in precision temperature measurement applications.
RESUMEN
In this work, a method is proposed and demonstrated for fabrication of chirped fiber Bragg gratings (CFBGs) in single-mode fiber by femtosecond laser point-by-point inscription. CFBGs with bandwidths from 2 to 12 nm and dispersion ranges from 14.2 to 85 ps/nm are designed and achieved. The sensitivities of temperature and strain are 14.91 pm/°C and 1.21pm/µÎµ, respectively. Compared to the present phase mask method, femtosecond laser point-by-point inscription technology has the advantage of manufacturing CFBGs with different parameter flexibilities, and is expected to be widely applied in the future.