Amplification of Electrostriction Mechanism of Photoacoustic Conversion in Layered Media.

In this work we have performed an analysis of electrostriction mechanism of optical to acoustical energy conversion on the interface of two materials with low optical absorption. We compared this method of conversion with widely used thermal conversion based on thin metal film. It was shown, that the contribution of electrostriction mechanism is significantly lower in case of homogeneous medium. We demonstrated the possibility to amplify the generated acoustic signal by excitation of the guided modes, which energy is localized in a thin (of about 200-400 nm thickness) dielectric layer. Due to high electromagnetic field energy concentration in the structure, local values of intensity increase by more than two order of magnitude in comparison to intensity of incident light, that also allows to increase the amplitude of the pressure correspondingly. Thus, in the project we propose the novel layered dielectric structures, in which electrostriction effect occurs due to excitation of the guided modes.