We report the efficient generation of high-contrast subpicosecond fifth-har
monic pulses with a Nd:glass laser. Highly reproducible 340-mu J, 850-fs pu
lses at 211 nm were generated in 0.5-mm-thick beta barium berate (BBO) crys
tal with a 33% energy conversion efficiency in the fifth-harmonic generatio
n stage. By use of fifth-harmonic pulses, a two-photon absorption coefficie
nt of beta = 2.45 +/- 0.15 cm/GW at 211 nm for the BBO crystal was measured
. (C) 2000 Optical Society of America [S0740-3224(99)01512-X] OCIS codes: 1
90.2620, 260.7190.