Repetitive modulation and passively Q-switching of diode-pumped Nd–KGW laser

Abstract

We report the operation of a passively Q-switched diode end pumped Nd 3+:KGW laser. Passive Q-switching operation was obtained by using a Cr 4+:YAG or Cr 4+:GGG as saturable absorbers. The free-running and the passively Q-switched characteristics of Nd:KGW were investigated and analyzed. At a free-running mode, a maximum slope efficiency of 46%, and an absorbed pumping threshold of 380 mW were obtained for 4.1 at.% doping level, with 1.5-W maximum output power at 3.60-W absorbed pumping power. The Nd:KGW laser beam quality exhibited a TEM 00 with M 2=1.6. The laser parameters were further analyzed as a function of the crystal heat sink temperature and the pump wavelengths. A passive Q-switched laser has been designed and operated, with a variety of Cr 4+ doped garnets employed as saturable absorbers. The laser produced modulated output in the multi-kHz frequency domain. The pulse width and the modulation frequency dependence of the passively Q-switched, repetitively modulated laser output vs. the diode pump power for Nd:KGW crystals, provides the conditions needed to enhance the modulation frequency and the peak power of diode-pumped Nd:KGW laser.