Conical scattering of laser beams in active dye solutions

The observation of conical scattering of dye laser radiation due to diffraction by a volume grating formed in the active medium by interference of the pump and scattered radiation waves is reported. Measurements are made of the dependences of the grating diffraction efficiency η on the pump intensity I and the absorption coefficient of the medium at the pump frequency α_ν. It is shown that the dependences obtained η(I) and η(α_ν) may be interpreted assuming the existence of absorption-induced stimulated scattering in the medium. The scattered radiation power is measured as a function of I and α_ν. It is concluded that allowance must be made for these processes as factors limiting the stimulated emission efficiency of pulsed dye lasers at high pump powers.