Temporal characteristics and dynamics of gain-switched Cr:YAG lasers

Temporal characteristics of tuned and fixed-wavelength Cr:YAG gain-switched oscillators are presented for 1064 nm Nd:YAG laser excitation. Three temporal excitation regimes have been studied with the pump laser operating in free-running and e-switched modes. Characteristic saturation and rollover behaviour of the Cr:YAG output energy with increasing pump energy is examined in terms of pump pulse duration, polarization orientation and fluence. Increased pump spot sizes yield higher values for the optimum pump energy and effective Cr:YAG energy scaling is demonstrated with only a slight threshold increase. A further enhancement in efficiency is obtained using 500 ns pump pulses. Control of the Cr:YAG pulse duration in the 160-300 ns range is obtained, using 6-80 ns pump pulses. The Cr:YAG laser output is shifted to the near infrared region using second harmonic generation in KTP.