Affiliation:
1. School of Electronic Information and Electrical Enginering, Chengdu University, Chengdu 130012, China
Abstract
We demonstrate fast writing of strong fiber Bragg grating (FBG) without hydrogen loading using 343 nm femtosecond pulses of only 7 μJ energy at 60 kHz repetition rates and a two-mask interferometer. The beam was focused to a 30–50 μm diameter along the fiber axis, greatly enhancing the peak power while avoiding damage to the masks. A refractive index modulation of more than 10−3 could be obtained in less than one minute exposure. To avoid the observed strong temperature gradient observed in the SMF-28 fiber, a galvo scanner was used to rapidly move the beam back and forth laterally up to 1 mm. FBG were written in SMF-28, as well as 20/400 μm fiber. In the latter fiber, better heat dissipation allowed us to write the FBG with the standard phase mask scanning technique, and a 0.28 mm Gaussian apodized FBG could be written.
Funder
Hangzhou Guanglian Technology