Threshold Conditions for 1-D Model of Laser Cavity Covered with Noble Metal Film

The threshold conditions for the natural modes of a solid-state laser model containing a flat-layered cavity of gain material are considered. The cavity is placed between a noble metal substrate and the same material superstrate film. We use the Lasing Eigenvalue Problem approach to find the mode-specific frequencies and the corresponding to them threshold gain index values. The results obtained clarify the effect of the noble metal film thickness on the lasing mode characteristics. This analysis can be used in the laser performance optimization.