| Scope and method of study. This thesis reports the investigation of the dynamic behavior of the gain function and the carrier temperature in semiconductor laser media. Modified rate equations are used as a basis for research. Analytical expressions are derived for relationship between density, chemical potential, energy density and temperature of carriers. Gain and carrier temperature dynamics are investigated by numerical simulations using the fourth order Runge-Kutta method.;Findings and conclusions. The model reveals a complex dynamic relationship between the gain coefficient and carrier temperature. In particular, it is found that a variety of gain nonlinearities at picosecond and sub-picosecond time scale can be described by the modified rate equations that include carrier temperature as a dynamical variable. The carrier temperature behavior is substantially different in amplifying and absorbing media. Carrier temperature exhibits a double-peak behavior when the medium is strongly absorbing. In weakly absorbing, transparent and amplifying media carrier the temperature has a single peak that is a result of interaction with external pulse. The medium appears to be transparent depending on external pulse energy and duration. The influence of free-carrier absorption and two-photon absorption are found to be most influential for high-energy pulses. Both these processes lead to substantial carrier heating. |
