Lasers with distributed feedback formed by diverging beams

A study was made of the possibility of tuning the emission frequency of organic dye lasers by establishing a distributed feedback in the active medium with the aid of beams of 1–6° angular divergence. Constantintensity lines, forming a dynamic grating, were hyperbolas, which made it possible to tune the emission frequency by moving the active medium along the axis of the interference zone. The use of high concentrations of dyes in solutions or of thin active media ensured that the spectral broadening of the stimulated emission line was considerably less than the tuning range achieved by moving the active medium.