Difference-frequency generation in the cavity of a dual-wavelength semiconductor disk laser: Effect of absorption of the short-wavelength radiation in the ’long-wavelength’ active region on the operation point stability

A difference-frequency generation in the external cavity of a dual-wavelength semiconductor disk laser (SDL) is numerically studied. The dual-wavelength SDL itself has been designed to emit two optical beams simultaneously – the short-wavelength beam (usually referred to as the pump) and the long-wavelength beam (signal). The study is performed with the help of the mathematical model based on a set of ordinary differential equations with a time delay. The model takes into account possible absorption of the pump radiation in the active region designed to provide gain for the signal. The steady state operation point, its stability, and transient dynamics of intra-cavity difference-frequency generator (ICDFG) are analyzed. As the pump radiation absorption exceeds the critical value, the operation point is shown to lose the stability within the certain interval of the primary pomp power. The steady-state instability of the ICDFG develops to the multi-scaled oscillations of high amplitude.