Phys.org  August 19, 2024 Researchers in Singapore have showed that the efficiency of spontaneous parametric down-conversion (SPDC) could be improved by harnessing many-body excitonic interactions present in the non-linear optical crystal. They showed that excitonic resonances and interexciton transitions could enhance the probability of SPDC. They benchmarked their ab initio many-body calculations using experimental polar plots of second harmonic generation in NbOI2, demonstrating the relevance of excitons in the nonlinear response. A strong double-exciton resonance in 2D NbOCl2 led to significant enhancement in the second order susceptibility. According to the researchers their work paves the way for the realization of […]