Chirped and tilted fiber Bragg gratings inscribed by femtosecond laser direct writing technology

Chirped and tilted fiber Bragg grating (CTFBG) was fabricated in SMF-28e fiber by using femtosecond laser line-by-line technology. The tilt angle and chirp rate of above-mentioned CTFBG were 8° and 10 nm/cm, the insertion loss, 3dB-bandwidth, filtering efficiency and central wavelength were 0.8 dB, 75 nm, 75% and 1511.38 nm, respectively. In addition, chirped FBG (CFBG) and tilted FBG (TFBG) were fabricated by using femtosecond laser line-by-line technology, and the spectral properties of CFBG, TFBG and CTFBG were compared and analyzed.