Effect of laser dye deterioration on performance

A previous analysis that described loss of gain in a dye solution as a result of photochemical decomposition by pump photons is refined and is extended to the situation where impurities absorb at the pump wavelength. A limitation in the first paper is that it described only a single absorption depth in the medium at a constant pump fluxI _p. The present examination includes the fall-off ofI _p and integrates the total signal output with depth for a single-pass amplifier operated in the fully saturated gain condition. The equations are simpler, but as before loss of output, expressed in terms of a quantum yield of laser decayQ _L, is minimized for a photochemically bleachable dye, and for one with high gain. Pumping in the vicinity of the absorption maximum is also advantageous.