On Generation of Pulsing Acoustic Waves in Globular Photon Crystals

Information is given regarding the generation of a new type of acoustic waves which are accompanied by pulsing variations in density of the material medium-globular photon crystal. The generation of such waves occurs as a result of the forced globular scattering of light in artificial opals. Giant pulses of the ruby laser with the 10-ns duration and power density of 108 W/cm2 on the sample surface were used as source of exciting radiation. During the forced globular scattering of light, the scalar acoustic waves of gigahertz range are excited and the Stokes constituents of the forced scattering arise which are shifted in frequency by 0.3-0.4cm-1 with respect to the wavelength (694.3 nm) of the exciting radiation. The maximal efficiency of conversion of the ruby-laser radiation to the Stokes forced globular scattering of light, when the investigated sample was placed in liquid nitrogen (T = 78 K), was 60%. The intensity of the directed scalar acoustic waves that were generated in the forced globular scattering was about 103 W/cm2.