Lasing schemes, cascade

Figure 1. Representative energy-level diagram and transitions for four-level and cascade lasing schemes vP and vL are the pump and laser frequencies wavy lines denote nonradiative transitions.

S2- 515 lasing was-obtained within 0.5 ys. As a result, sufficient population buildup occurred in 5 to achieve 515- 516 oscillation before significant spontaneous decay from the 5l5 state. Cascade lasing schemes of Ho3+ in Gd3Ga50]2 crystals including 16 18 transitions were reported recently (Z8). 

An examination of the trivalent actinide energy level schemes reveals several possibilities for laser action. These are discussed in light of the general properties cited above. Only conventional broadband optical pump sources are considered. Obviously with selective laser excitation and cascade lasing schemes, stimulated emission from many more states should be possible, but these special situations are too numerous to be considered in detail here. 

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