An integrated acoustooptic frequency shifter driven by surface acoustic wave for 1.55μm optical wavelength

An integrated acoustooptic frequency shifter in a crossed-channel waveguide is demonstrated at an optical wavelength of 1.55 mum. A novel tapered device was designed to make the acoustooptic interaction region longer and thus the driving surface acoustic wave (SAW) power lower, and the device was fabricated by the proton-exchange method and post-annealing in a 128 rotated Y-cut LiNbO3 substrate. At SAW power of 1.4 W, a 40% diffraction efficiency and a bandwidth of 5 MHz centered at 196 MHz were obtained. The frequency shift of Bragg diffracted light was confirmed in an optical heterodyne experiment.