Abstract: An eyesafe laser system includes a Q-switch crystal formed of a semiconductor host material having noncentrosymmetric tetrahedral substitutional sites doped with transition metal ions in concentrations from about 0.001 to about 0.10 atomic percent, which functions as to be a saturable absorber of light at eyesafe wavelengths with a relatively long relaxation lifetime. Co.sup.2+ :ZnSe has been demonstrated to have advantageously high absorption cross section and advantageously high relaxation lifetime at both 1.54 .mu.m (Er:glass laser) and 1.6 .mu.m (Er:YAG laser). Other candidate host materials include other zinc chalcogenides, cadmium chalcogenides and zinc oxide.

Abstract: A laser system includes a laser resonator cavity having a resonant axis and a lasing element within the laser resonator cavity. The lasing element emits, under stimulation, light at a wavelength of from about 0.95 to about 1.65 micrometers. There is a flash lamp which optically pumps the lasing element to emit light. A Q-switch crystal lies along the resonant axis within the laser resonator cavity. The Q-switch crystal is formed of a host material having a concentration of Co.sup.2+ ions therein, so as to be a saturable absorber of light of a wavelength of from about 0.95 to about 1.65 micrometers. The Q-switch crystal is preferably Co.sup.2+ -doped yttrium-scandium-gallium garnet or Co.sup.2+ -doped yttrium-aluminum garnet.

Abstract: A glass fiber laser system includes a laser resonator cavity having a resonant path and an erbium-doped glass fiber lasing element with an output of from about 1.5 to about 1.6 micrometers within the laser resonator cavity. A light source directed into an input end of the glass fiber lasing element optically pumps the lasing element to emit light. A passive Q-switch lies along the resonant path within the laser resonator cavity. The Q-switch is formed of a host material having a concentration of uranium ions therein, so as to be a saturable absorber of the light emitted by the lasing element. The Q-switch is preferably a uranium-doped fluoride crystal such as U:CaF.sub.2, U:SrF.sub.2, or U:BaF.sub.2.

Abstract: A laser system includes a laser resonator cavity having a resonant axis and an Er:glass, Er:YAG, or other lasing element with an output of from about 1.4 to about 1.65 micrometers within the laser resonator cavity. A flash lamp optically pumps the lasing element to emit light. A Q-switch crystal lies along the resonant axis within the laser resonator cavity. The Q-switch crystal is formed of a host material having a concentration of U.sup.2+ ions therein, so as to be a saturable absorber of the light emitted by the lasing element. The Q-switch crystal is preferably a U.sup.2+ -doped fluoride such as U:CaF.sub.2, U:SrF.sub.2, or U:BaF.sub.2.