Pushing periodic disorder induced phase-matching into deep-ultraviolet spectral region
(PHYSorg.com Physics)

Phase matching condition is the key criteria for efficient nonlinear frequency conversion. Here, Scientists in China employed an additional periodic phase (APP) technique to meet the phase-matching condition in quartz crystal and experimentally demonstrated the efficient nonlinear frequency conversion from the visible to the deep-ultraviolet spectral region. The APP theory and generated visible to deep-ultraviolet radiation would revolutionize next-generation nonlinear photonics and their further applications.