Influence on the Parameters of GaAs-based HG PCSS Switching in Lock-On Mode at Laser Radiation With a Wavelength of 355 nm and 1064 nm

In this paper, it has been experimentally found that the efficiency of HG PCSS switching based on GaAs:Cr is higher from radiation with a wavelength of 355 nm with an average front duration of 2.7 ns in comparison to triggered by an optical pulse with a wavelength of 1064 nm and a front duration of 11.6 ns. The difference in optical energy for 355 and 1064 nm is 14 times
$(25\ \mu\mathbf{J}$
vs.
$345\ \mu \mathbf{J}$
) and in duration is 3 times (5.7 ns vs. 16 ns). The experiment was carried out at a charging voltage of ∼ 13.7 kV with output pulses with an amplitude of 6.6 kV and 5.9 kV, which corresponds to the PCSS resistance at the time of switching 2.3 and 7.7 Ohm with currents of 132 A and 118 A. Application of a laser pulse with a shorter wavelength PCSS switching leads to a 3-times decrease in PCSS resistance. The temporal characteristics of the output pulse obtained during the experiment for laser beam with wavelength of 1064 nm are the front duration of 4.3 ns and the pulse FWHM of 39.3 ns. Under switching by radiation with a wavelength of 355 nm, the duration of the front of the output pulse equals 6 ns, but the FWHM duration is 33 ns. A longer pulse front demonstrates an increased value of the inductance of the conducting channel, which accordingly indicates a decrease in its cross-section. These factors indicate a significant increase in conductivity when the key is irradiated at a wavelength of 355 nm.