Theoretical study of the characteristics of a continuous wave iron-doped ZnSe laser

A theoretical model describing the dynamic process of a continuous-wave Fe2+: ZnSe laser is presented. The influence of some of the operating parameters on the output characteristics of an Fe2+: ZnSe laser is studied in detail. The results indicate that the temperature rise of the Fe2+: ZnSe crystal is significant with the use of a high power pump laser, especially for a high doped concentration of crystal. The optimal crystal length increases with decreasing the doped concentration of crystal, so an Fe2+: ZnSe crystal with simultaneous doping during growth is an attractive choice, which usually has a low doped concentration and long length. The laser pumping threshold is almost stable at low temperatures, but increases exponentially with a working temperature in the range of 180 K to room temperature. The main reason for this phenomenon is the short upper level lifetime and serious thermal temperature rise when the working temperature is higher than 180 K. The calculated optimum output mirror transmittance is about 35% and the performance of a continuous-wave Fe2+: ZnSe laser is more efficient at a lower operating temperature.