| 摘要 |
PURPOSE:To generate a surface acoustic wave (SAW) which interacts efficiently upon even light having spread, by connecting plural finger-shaped electrodes, which are bent to an arc shape, alternately to a pair of common electrodes. CONSTITUTION:An IDT20 has plural arcuate finger electrodes 31 and 32 whose centers are projected toward a light diffraction position, and these finger electrodes 31 and 32 are connected alternately to a pair of common electrodes 21 and 22. Intervals between finger electrodes 31 and 32 are related to the wavelength of an SAW to be generated. The curvature (or curvature radius R) of finger electrodes 31 and 32 is determined in accordance with the angle of spread of the light discharged from an optical waveguide 16. When an ultrasonic signal is applied between common electrodes 21 and 22, the SAW is generated from finger electrodes 31 and 32, and this SAW is propagated while being expanded on an optical guide layer 12 in various direction perpendicular to tangential direction of finger electrodes 31 and 32.
|
