Mid-infrared fluoroindate glass long-period fiber grating by femtosecond laser inscription

Abstract

A long-period fiber grating (LPFG) was fabricated in a home-made fluoroindate fiber using a femtosecond laser, and attenuation peaks as strong as −17 dB, with sharp and predictable spectral resonances, were obtained over the transmission spectrum. A strain up to 2000 με applied on the LPFG yielded a resonant wavelength redshift of circa 8.46 nm. The strain sensitivity of this LPFG in fluoroindate fibers could pave the way for a new range of applications in the mid-infrared wavelength regions, such as tunable optical rejection band filters in fiber amplifiers and sensing devices.