Changes in the profile and state of polarisation of a short light pulse (λ ~ 1.06 μm) during propagation in a YAG : Cr4+ crystal

An investigation was made of changes in the profile and state of polarisation of a short (25 ns) resonant light pulse (λ ~ 1.06 μm) during its propagation in a YAG : Cr⁴⁺ crystal. The experimental results were in good agreement with a theory in which the absorption of light by the Cr⁴⁺ impurity centres in a YAG crystal is described phenomenologically as a consequence of the interaction of light with three orthogonal groups of resonant linear dipoles. The result demonstrated the fleasibility of controlling the profile of a light pulse propagating through polariser – YAG : Cr⁴⁺ crystal – polariser system. The application of a single-frequency pulse to this system generated output pulses with two or three intensity maxima. This was a direct result of a self-induced change in the state of the polarisation of the light in the YAG : Cr⁴⁺ crystal at the saturation absorption stage.