Amplification of the electrostriction mechanism of photoacoustic conversion in layered media

Abstract

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