SUPPRESSION OF AMPLIFIED SPONTANEOUS EMISSION FROM A 4-PASS DYE-LASERAMPLIFIER

We demonstrate a new design for a four-pass dye laser amplifier that c an be used to reduce amplified spontaneous emission (ASE) in the ampli fier output beam. Compared with the results obtained from normal opera tion of the four-pass dye laser amplifier without a frequency-selectiv e device, by using a diffraction grating in the amplifier we can reduc e the ASE ratio by a factor in excess of 10 and increase output energy by similar to 4%. The obtained ASE ratio of the four-pass amplifier s ystem is <1.5%. (C) 1998 Optical Society of America.