Model for an active medium based on a (Cr,Tm,Ho):YSGG crystal

A new model has been constructed for the active medium (Cr,Tm,Ho):YSGG (corresponding to generation on the ⁵I₇→⁵I₈ transition of the Ho³⁺ ion). Certain features of the filling of the ³H₄ level of the Tm³⁺ ion and of the ⁵I₇ level of the Ho³⁺ ion during steady-state pumping which affect the basic generation characteristics of this laser–its differential efficiency and its lasing threshold—have been identified on the basis of this model. Experimental data agree with theoretical predictions.