Final Report Summary - PETAL (Polarization condEnsation for Telecom AppLications)
The first results of the PETAL project was to provide a theoretical model of this counter-propagating effect in order to fully understand and master the polarization condensation phenomenon. In particular, we have derived some design rules which enable to predict the different dynamics generated by the optical feedback within the Omnipolarizer. Due to the particular boundary conditions imposed by the reflective element inserted at fiber end, we have theoretically and experimentally identified 3 working regimes which depend on the power ratio between both counter-propagating beams. For nearly equal powers, the Omnipolarizer can operate as an ideal polarizer and thus enables to repolarize any input signal; experimental demonstration has been successfully achieved on a 40-Gbit/s telecom signal and represents the first experimental proof-of-principle of the polarization condensation phenomenon. Then for a ratio of powers below unity, the device becomes bistable and can operate as a digital beam splitter. We have exploited this bistability to develop an optical memory as well as an all-optical routing device for optical packets in a 10-Gbit/s experiment. Finally, when a strong power imbalance is applied between the forward and backward signals, we have also observed a chaotic behaviour within the Omnipolarizer which has been exploited to demonstrate an all-optical polarization scrambler as well as a random bit generator. Finally, all these regimes of operation have been exploited in a combine experiment to provide a novel approach of securing or spying 10-Gbit/s optical transmissions.