Baseband integrated acousto-optic frequency shifter

Abstract
A novel baseband integrated acousto‐optic frequency shifter with a −3 dB tunable bandwidth of 121 MHz (from −61 to 60 MHz) at the optical wavelength of 0.6328 μm has been constructed in a Y‐cut LiNbO3 waveguide, 0.2×1.0×2.0 cm3 in size. Suppression of the various unwanted components by as much as 50 dB has been accomplished. Since the frequency‐shifted light propagates in a fixed direction, irrespective of the magnitude of frequency shift, this baseband acousto‐optic frequency shifter can be readily used in fiber‐optic systems.