High-performance guided-wave acoustooptic beam deflectors

Results of recent experiments involving guided optical waves and surface acoustic waves have demonstrated that it is possible to achieve very efficient interaction with noncollinear, coplanar Bragg diffraction in LiNbO3 substrate.1 Efficient diffraction results from the fact that both the optical and the SAW are confined in one dimension and that the frequency range of the SAW may be chosen to facilitate a good matching between the confinement of the optical waves and the penetration depth of the SAW. In particular, by employing multiple surface acoustic waves (Fig. 1), deflectors with very large diffraction efficiency-bandwidth product and excellent beam quality have been realized most recently. 1 For example, the frequency response and the light beam quality of a deflector, which has a 360-MHz bandwidth,2 are shown in Figs. 2 and 3, respectively. Total electric drive power of only 200 mW was required to diffract 50% of the incident light power. This particular deflector has deflected a light beam of a 4-mm aperture into 400 resolvable spots at a random-access switching time of 1.24 μsec. The above combination of performance figures far exceeds that obtained previously. It should be possible to achieve even better performance figures by optimizing the optical waveguide and surface acoustic wave parameters.