Four-level lasing schemes

Fig. 3J2. The four-level laser scheme. Pumping transition is I, lasing transition 3, nonradiaiive uansitions 2 and 4. On the right-hand side the level notation for Nd for the case of the 1064 nm laser action is given. H denotes levels above F3/2 further I11/2 cannot be thermally populated since it is about 2000 cm above the ground state...

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.

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