Beam-quality measurements on solid-state dye lasers using nonconfocal unstable resonators

摘要

This paper reports on a systematic study of the beam quality of solid-state dye lasers for different resonator designs, The resonators investigated include: multimode stable, hard-edge unstable, and unstable with a graded-reflectivity mirror (GRM) output coupler. The purpose of the work was to investigate the conditions under which good beam quality can be achieved, and to examine the possible trade-off between beam quality and energy extraction efficiency. Beam quality was quantified through conventional M~2 measurements. A hard-edge unstable resonator of magnification approx = 2.5 produced a beam of M~2 approx = 11 - 12 at a PRF of 2 Hz and a pump flux of 5 MW/cm~2. The value increased to approx = 18 - 19 at a pump flux of 20 MW/cm~2. This can be compared with an M~2 of approx = 140 - 150 with the multimode stable resonator. Preliminary measurements with the GRM resulted in M~2 values of approx = 5 to 6 at 5 MW/cm~2.