The Study Of Cr⁴⁺:Mg₂SiO₄Crystal As Q-switching Device And Gain Media

Recently, Cr4+:Mg2SiO4is a key crystal in doped Cr crystal investigated. It canbe as laser crystal owing to large emission cross and high quantum efficiency. Nowthe tuning band1136-1364nm can be achieved because of wide absorption spectrumand emission spectrum, which fills in the blank of tunable solid laser.1064nm laserQ-switching and mode locking pulses can be obtained as saturable absorber.In this paper, Cr4+:Mg2SiO4crystal was applied in gain switch laser pumpedusing graphene Q-switching1.06μm laser pulse. Via changing the energy of1.06μmlaser pulse, variety of pulse width and build-up time of1.22μm has been observed.when the pumped pulse width and energy is75ns and83mJ respectively,1.22μmlaser pulse build-up time is68.7ns.Cr4+:Mg2SiO4crystal of initial transmission T0=40%as a component in LDpumped solid laser, the change of the Q-switching with pumped laser power has beenobserved. By using Cr4+:Mg2SiO4crystal as saturable absorber in Q-switchingdevices, we find that Q-switching pulse width decrease almost linearly with theincrease of pumped power and52ns Q-switching pulse was achieved when thepumped power is6.454W.In complex cavity pumped by flash lamp, Cr4+:Mg2SiO4crystal was regarded ascomponent of1.06μm laser Q-switching and gain media. We studied theoretically andexperimentally the dual-wave output characteristic. Through changing the pump voltof Nd:YAG crystal pulse flash lamp, we observed the change tendency of pulse widthand energy of1.06μm and1.22μm laser, and1.22μm laser build-up time. The result isthat pulse energy of1.06μm and1.22μm laser increase with the increasing of pumpvolt, but the pulse width keeps constant nearly. Meanwhile, build-up time of1.22μmlaser pulse decreases with the increasing of pump volt.We also studied that1.06μm and1.22μm dual-wave pulses are carried outoutside cavity sum frequency by applying KTP. Assuming the pulse is Gaussian,conversion efficiency of sum frequency is directly in proportion to the overlapping region of the dual-wave pulse, that is to say conversion efficiency of sum frequencyrelate to the dual-wave pulse energy, width and peak value interval time. Thus theexperiment results are consistent with the theory analysis.