Dynamic properties of an electrooptic DKDP switch in the microsecond range

An intracavity method was used in an experimental investigation of the dynamic processes in a Pockels cell made of a DKDP single crystal. The cell was placed inside a laser resonator operating in the free-running regime and characterized by an external negative feedback loop. For the first time the time dependence of the transmission of the switch was determined during the operation of a laser and it was found that acoustic vibrations affected the modulation properties of the switch. Another reason for the excitation of acoustic vibrations was the electric field of radiation of intensity in excess of 10⁴ W/cm² crossing the crystal. Clearly, this field also altered the anisotropy of the crystal giving rise to abrupt changes in the switch transmission under the influence of the individual lasing spikes. In the presence of a negative feedback loop this effect was manifested by self-excitation of hf (in excess of 10⁶ Hz) fluctuations of the laser radiation power at the peak of a pulse. These two effects (acoustooptic and photorefractive) could alter greatly the modulation efficiency of the switch dealing with stochastic spike radiation of intensity in excess of 10⁴ W/cm².