Abstract

Thermally induced fluctuations in the index of refraction constitutes a nonlinear effect which may be particularly suitable for high-power applications involving phase conjugation at relatively short wavelengths (visible, UV). The mechanism involves generation of thermal gratings precipitated by light absorption in a liquid {e.g., an absorbing dye solution). Thermalization of the optically excited absorber molecules gives rise to periodic temperature and density fluctuations which result in corresponding spatial modulations of the index of refraction. These act as a phase grating in the scattering of incident light. Degenerate-four-wavemixing (DFWM) experiments mediated by this mechanism resulted in sizable conjugate returns (>3G0%) in both the visible¹ and UV² in previous experiments.

© 1983 Optical Society of America