Abstract: An acoustic generator, comprising: a source of electro-magnetic radiation; a waveguide coupled to said source; and at least one absorbing region defined in said waveguide, said region being selectively absorbing for portions of said radiation meeting at least one certain criterion and having significantly different absorbing characteristics for radiation not meeting said criterion, both of said radiation portions being suitable for conveyance through said waveguide, wherein said absorbing region converts said radiation into an ultrasonic acoustic field. Optionally, said region comprises a volumetric absorber. Alternatively or additionally, said region comprises a plurality of regions.

Abstract: A method of coupling optical energy comprising: generating a first beam of optical energy; generating a second beam of optical energy coherent with the first beam; polarizing optical energy from the first and second beams in a same direction; and transmitting the polarized optical energy from the first and second beams into a photorefractive body so that the energy interferes in the body to generate an interference pattern that is extant in substantially all the volume of the body.