Lumped Dissipation Induced Quasi-Phase Matching for Broad and Flat Optical Parametric Processes

Distributed dissipation in optical parametric processes has attracted renewed interests recently due to its rich physics including modulation instability, gain broadening, unidirectional energy transfer etc. Due to difficulties in practical implementation, lumped dissipation are investigated in this work as an alternative approach which can be realized more conveniently. Strong similarities are found between lumped and distributed dissipation. While distributed losses contribute to non-hermitian phase matching, lumped dissipation is shown to be a simple and universal quasi-phase matching method. Experimental validations of gain broadening and flattening in normal and anomalous dispersion regions are presented. As an application to wavelength conversion, enlarged conversion bandwidth when dissipation is introduced to the signal wave is revealed.