Abstract:
An experimental investigation was made of the influence of spatial filtering on the brightness of the output beam from the amplifying channel of a high-power laser system in which the active elements were Nd3+-doped phosphate glass rods. It was found that the brightness of the output beam could be increased substantially by an appropriate choice of the parameters of a vacuum spatial filter. A beam 40 mm in diameter with a peak intensity of 3.4 GW/cm2 was obtained. Small-scale self-focusing did not cause appreciable energy losses in an angle of 0.25 mrad. The possible criteria for estimating the influence of small-scale self-focusing on the brightness of the beam being amplified were considered. These criteria should be useful in the development of systems of amplifying channels with periodic spatial filtering.