Surface-Acoustic-Wave-Driven Acoustooptic Modulator with Wide Wavelength Range for Visible Laser Light

摘要

To realize an acoustooptic modulator (AOM) in which laser lights of the three primary colors red, green, and blue can be modulated by the same modulator at the same driving frequency, a waveguide-type AOM driven by a surface acoustic wave (SAW) was applied in the visible range. The waveguide-type AOM for visible laser light was fabricated on a 128° V-cut LiNbO_3 substrate on the basis of the design of the waveguide shape using the beam propagation method, and the diffraction properties were measured. For the optical wavelengths of 633 and 532 nm, according to the analytical results, a maximum diffraction efficiency range from 73 to 85% was obtained. On the other hand, in contrast to the analytical results, the maximum diffraction efficiency for the optical wavelength of 473 nm was as small as 47%. However, a diffraction efficiency of at least 47% for laser lights of the three primary colors was obtained at the same driving frequency. The experimentally obtained driving SAW powers required to obtain the maximum diffraction efficiency were several times as large as the theoretical values.