Gigahertz Acousto-Optic Modulation and Frequency Shifting on Etchless Lithium Niobate Integrated Platform

Acousto-optic interactions involving propagating phonons can break the time-reversal and frequency-modulation symmetry of light. However, conventional acousto-optic modulators based on bulk materials have frequency bandwidth limited to hundreds megahertz due their large structural sizes. Here, we experimentally demonstrate gigahertz single-sideband modulation an etchless lithium niobate integrated platform by using photonic bound states in continuum. The upper- or lower-sideband light be obtained conveniently choosing specific combinations input output channels. Under this scheme, realized a 3-GHz shifter, which operates C-band with 3-dB ~35 nm. extinction ratios upper(lower)-sideband modulated lower(upper)-sideband unmodulated are >44 (47) 25 (23) dB operating bandwidth. frequency-shifted further processed amplitude modulation. Therefore, demonstrated enable many applications such as optical signal processing, sensing, ion trapping.