Propagation of the lasing zone in dye solutions with a bleaching wave

Measurements were made of the propagation velocity of a bleaching wave in a laser active medium during a period 0.5 μs at high (10²⁴–10²⁵ photon · cm ^– 2 · s ^– 1) pump intensities. Some features of the bleaching mechanism of the dye molecules were identified by comparing the theoretical and experimental results. The lasing efficiency in the 517 nm range reached 40% in the active medium of a bleaching-wave laser utilizing an ether solution of coumarin 6 and 1,4–diphenylbutadiene. The lasing zone propagated in the solution at a velocity of 15 km/s. The divergence of the bleaching-wave laser radiation was 3–10 times less than the divergence of a conventional dye laser with a steady-state medium.