2018/05/31 by Rachel F. Offer, Dalius Stulga, Erling Riis +2
Physics and Astronomy · #physics.atom-ph
paper · pdf · doi:10.1038/s42005-018-0077-5
published as Communications Physics 1, 84 (2018) · Fully revised to include referees' improvements and journal requirements. Supplementary material is included as an ancillary file
arxiv created 2018/11/28 · arxiv updated 2018/11/30
Laguerre-Gauss beams, and more generally the orbital angular momentum of light (OAM) provide valuable research tools for optical manipulation, processing, imaging and communication. Here we explore the high-efficiency frequency conversion of OAM in a four-wave mixing process in rubidium vapour. Conservation of the OAM in the two pump beams determines the total OAM shared by the generated light fields at 420 nm and 5.2 um - but not its distribution between them. We experimentally investigate the spiral bandwidth of the generated light modes as a function of pump OAM. A small pump OAM is transferred almost completely to the 420 nm beam. Increasing the total pump OAM broadens the OAM spectrum of the generated light, indicating OAM entanglement between the generated light fields. This clears the path to high-efficiency OAM entanglement between widely disparate wavelengths.