Waveguide-Type Multifrequency Acoustooptic Modulators

Multifrequency acoustooptic modulators (MF-AOMs) utilizing a Ti-diffused LiNbO3 waveguide are investigated for application to high-speed laser beam scanners. The Z-propagation of a light beam is free from optical damage. The surface acoustic waves (SAWs) for the MF-AOM are excited at 8 frequencies from 350 to 490 MHz every 20 MHz. Therefore, the MF-AOM generates 8 light beams using a TE-TM mode conversion. No optical damage at 633 nm wavelength is observed up to a power density of 2 kW/cm2. The AO diffraction efficiency per light beam, rise time and total efficiency of the device at 633 nm wavelength are 6%, 26 ns and 19%, respectively.