Step-like all-optical decision function using nonlinear polarisation rotation in a Nonlinear Optical Loop Mirror and in a subsequent fibre section with output polarisation selection

摘要

We propose and study numerically a fibre-based scheme designed to generate a step-like optical decision function for ultrafast data processing applications. The setup includes two main sections disposed in series: a Nonlinear Optical Loop Mirror with an output polariser on the one hand, and a circularly birefringent fibre span with a quarter wave retarder at the input and a polariser at the output on the other hand. Both sections operate through nonlinear polarisation rotation, and the switching characteristic is controlled through the light ellipticity, which can be adjusted by setting properly the orientation of the input polarisation, and by rotating the wave retarder and the two polarisers. For proper adjustment of these four parameters, a step-like optical decision function with ～10 dB/dB steepness is predicted. In the frame of all-optical regeneration, the setup allows eliminating ～76% peak-to-peak amplitude fluctuations on the marks and ～30% relative power on the spaces. We believe that this architecture should be considered for the design of ultrafast transmission networks and in the frame of all-optical computing applications.