Tunable Acoustically-Induced Fiber Gratings Based on the Anti-Resonant Hollow-Core Fiber

We demonstrate a tunable grating in a six-hole anti-resonant hollow core fiber (AR-HCF) based on acousto-optic interaction, by applying flexural acoustic waves along the fiber axis. In the experiment, the resonant wavelengths could be electrically tuned within a range of 1329 nm to 1353 nm, consistent with the simulation results. The tuning range is primarily limited by the narrow response bandwidth of the acoustic field of AR-HCF. The minimum 3 dB bandwidth is 4.5 nm, and the maximal notch depth is 12.5 dB. Acoustically-induced fiber gratings benefit from the high damage threshold, low dispersion, and low nonlinearity characteristics of AR-HCF, can serve as tunable filters in fast-tunable high-power lasers, long-distance fiber communication, and WDM networks. Additionally, due to the low thermal sensitivity and radiation resistance characteristics of AR-HCF, these gratings could be applied in fiber grating sensing and laser transmission, particularly in radiation environments.