Faraday mirror stabilization scheme for nonlinear polarization rotation in optical fibers: model and applications

Abstract

Summary form only given. The potential of nonlinear polarization rotation (NPR) in waveguides is huge as it can be exploited for a large variety of ultrafast devices like optical switches, logic gates, intensity discriminators, nonlinear filters, or pulse shapers. However, an inherent problem to all this applications is the stability of the output polarization state. Fluctuations of the linear birefringence caused by temperature changes, drafts in the fiber environment, and vibrations generally disturb a proper functioning. We propose an elegant method to remove these detrimental fluctuations in a passive way by employing a Faraday mirror (FM) and a double pass of the fiber where NPR takes place. The proposed stabilization scheme has the additional advantage that the double pass allows for a reduction of the fiber length times pump intensity value by almost a factor of two. A model is developed that allows for an intuitive understanding of the action of the linear and nonlinear birefringence during the go- and return-path. Besides giving good insight in the underlying physical processes, it directly shows that the effect of NPR adds whereas the detrimental effects of the (fluctuating) linear fiber birefringence are removed.