DPSK regeneration: phase and amplitude noise suppression based on Kerr medium

Abstract

The scope of this thesis is to identify and propose new schemes for Deferential Phase Shift Keying (DPSK) regeneration. DPSK modulation format presents increased robustness against ASE noise, which makes it strong candidate for use in long haul transmission systems. To achieve reasonable DPSK regeneration suppression of both the amplitude and phase noise is required. Three types of all-optical regenerators that make use of a Kerr medium, which can be a highly nonlinear fiber are analyzed. The first scheme is based on a modified nonlinear optical loop mirror (NOLM), with a subsequent addition of a bidirectional attenuator (DANOLM). The bidirectional attenuator allows to counterbalance the generation of the phase noise generated by the Gordon Mollenauer effect inside the Kerr medium. The second type of optical regenerator is based on the Self Phase Modulation (SPM) effect and offset filtering. Finally a novel scheme derived from the concepts of two former setups is presented and compared to the previous proposed. The operational conditions for optimum noise rejection are identified for each one of them. Through numerical simulations and detailed benchmarink we identify that our proposal outperforms all the schemes that have been presented previously in literature.