All-fiber broadband spectral acousto-optic modulation of a tubular-lattice hollow-core optical fiber

We demonstrate a broadband acousto-optic notch filter based on a tubular -lattice hollow -core fiber for the first time to our knowledge. The guided optical modes are modulated by acoustically induced dynamic long -period gratings along the fiber. The device is fabricated employing a short interaction length (7.7 cm) and low drive voltages (10 V). Modulated spectral bands with 20 nm half -width and maximum depths greater than 60% are achieved. The resonant notch wavelength is tuned from 743 to 1355 nm (612 nm span) by changing the frequency of the electrical signal. The results indicate a broader tuning range compared to previous studies using standard and hollow -core fibers. It further reveals unique properties for reconfigurable spectral filters and fiber lasers, pointing to the fast switching and highly efficient modulation of all -fiber photonic devices. (c) 2024 Optica Publishing Group