Reflections From A Dynamic Grating In A Dye Solution

Abstract

In addition to results of earlier experiments where Bragg scattering from a distributed feedback dye laser is observed, in the experiment described here the occurrence of a phase conjugated reflected beam is demonstrated. It is shown that a distributed feedback laser can be used as a frequency selective reflector for a seperate dye laser. Some time ago Golub and Shuker investigated the feasibility of optical switching by Bragg scattering of a light beam from a spatially modulated gain grating. This grating formed the basis of a distributed feedback dye laser (DFDL) and the reflection was only visible if the DFDL was pumped above threshold. In that case reflectivities of more than 100% for small input signals could be obtained. Golub and Shuker emphasized that in their experiment phase conjugation could not occur. Their main argument was, that the probe beam and the pump beams had completely different origins. Consequently these beams had no constant phase relation, and hence degenerated four-wave mixing leading to phase conjugation was excluded.