Fiber Bragg grating inscription in few-mode highly birefringent microstructured fiber

In this paper we present the technology of fiber Bragg grating (FBG) inscription in novel highly birefringent (HB) few-mode microstructured fibers (MSF) with two different – nanosecond and femtosecond – lasers in a Talbot interferometer set-up. The spectral characteristics of FBGs written in the core region of the investigated fiber, with particular modes represented by dual-peaks, are presented and discussed. Furthermore, we calculate the basic fiber parameters (mode effective refractive index and phase modal birefringence) from the spectral characteristics and show very good agreement with the performed numerical fiber characterization. We expect the results of our experiments to be very useful in future development of FBG sensors based on novel HB MSFs, with enhanced sensitivity of higher order modes.