Dissipative collinear weakly coupled acousto-optical states

Abstract

We investigate the components of dissipative multi-wave solitons in the form of three-wave weakly coupled states originating within the collinear acousto-optical interaction due to acoustic waves of finite amplitude. This investigation is carried out in a square-law nonlinear birefringent medium with linear optical losses, theoretically and experimentally. Theoretically, we study the three-wave collinear acousto-optical interaction using several acoustic pulse profiles, with the cases of infinite support (when the acoustic pulse envelope is gradually vanishing on the boundaries) and compact support (when acoustic pulse envelope is cut down on the boundaries), and consider the appropriate boundary conditions in a quasi-stationary regime with the phase mismatch. As a theoretical result, one has found that the system can be described; in particular, by the cnoidal Jacobi elliptic functions whose limiting cases lead to hyperbolic and trigonometric solutions. The experiments dedicated to examine these theoretical results have been done with a X-ray irradiated α-quartz crystalline cell enabling the collinear acousto-optical interaction. The cell used the pure longitudinal acoustic wave with the frequency mismatch along the 6 cm interaction length. Two types of acoustic pulses had been generated, namely, hyperbolic-secant pulse (infinite support) and a bounded rectangular pulse (compact support). During these experiments one had observed the optical components peculiar to the mismatched weakly coupled states. Rather well agreement between the theoretical model, simulated numerically, and the obtained data of measurements for the frequency detuning, acoustic power density, and efficiency of the coupled states localization have been achieved.