Untersuchung der Multimode-Emission von optisch gepumpten Halbleiter-Scheibenlasern im Hinblick auf effiziente intrakavitäre Differenzfrequenzerzeugung

Optically pumped semiconductor disk lasers using an external resonator (VECSELs) are highly interesting laser systems providing both high power operation and good beam quality. Furthermore, the external resonator makes this laser a versatile platform for accessing new emission wavelengths through intracavity frequency conversion processes. In particular, a VECSEL can be forced into two-color operation which, in combination with a nonlinear crystal, enables terahertz generation through intracavity difference frequency generation. Realizing a two-color emission in which both colors experience amplification from a common carrier reservoir is not a trivial task, as competition for gain between the lasing modes leads to complex emission dynamics. This dissertation presents essential investigations on the multi-mode emission in an optically pumped semiconductor disk laser. The work focuses both on the evolution of the spectral composition of the laser emission as well as on the characterization of the temporal dynamics of the emission in the two-color operation regime. For the configurations under investigation, parameters are identified which play a key role for the emission stability. The findings enable the definition of operating conditions under which intracavity difference frequency conversion is efficient and reasonable.