Erbium 3‐μm laser as an upconversion system

Abstract

The possibilities to obtain efficient 3‐μm lasing in erbium systems on the self‐saturated transition ⁴I_11/2→⁴I_13/2 are analyzed. In the frame of the mathematical model based on analytical expressions for population inversion, photon flux density, and quantum efficiency, obtained in the stationary regime, and which explains the main characteristics of 3‐μm generation, the influence of various interaction mechanisms such as cross‐relaxations, transfer to impurities, excited‐state absorption (ESA) and so on is analyzed. It is shown that, although ESA from the terminal laser level could improve the generation characteristics, the driving mechanism for 3‐μm erbium lasers is the cooperative upconversion from the terminal laser level. © 1996 Society of Photo−Optical Instrumentation Engineers.