Routes to complexity in the light output of mode-locked lasers

Abstract:

The investigation of complex laser structures, in this case a two section mode-locked laser with optical self feedback, can be both a test bed for nonlinear dynamics as well as a guide for device optimization of pulsed light sources. In this talk we discuss how complex quasi-periodic dynamics emerges with increasing mode number in these devices. The focus will be on identifying qualitative changes of the output pulse trains by means of bifurcation analysis. Further, in the limit of large mode numbers, i.e. very short pulses, the usual modeling approach which assumes instantaneous absorption or emission processes, is not sufficient any more. Instead, coherent effects induced by the dynamics of the material polarisation inside the gain medium become important and need to be modeled by optical Bloch equation. In the second part of the talk the impact of this additional dynamical degree of freedom on pulse shape and stability of the laser output will be discussed.