Breaking the intra-cavity degeneracy of vortex modes
Presented by Mr. Darryl NAIDOO on 9 Jul 2014 from 11:50 to 12:10
Type: Oral Presentation
Track: Track C - Photonics
We investigate an intra-cavity approach for the realisation of arbitrary orbital angular momentum (OAM) mode selection of opposite handedness by implementing a technique of spin angular momentum (SAM) to OAM coupling through a q-plate. It is well known that the spatial intensity distribution of laser modes with opposite handedness (such as +l and -l) in their helicoidal wavefronts are indistinguishable and in the context of a laser cavity they also posses identical intra-cavity losses. The discrimination of either mode thus proves improbable and is accredited to the degeneracy of this set of angular modes. While many studies claim pure OAM mode selection, they suffer from inconclusive confirmation on the state of OAM at the output. In this study we show the controlled intra-cavity selection of pure OAM LG0l modes of opposite handedness and demonstrate it experimentally. With this we also present a direct approach to realise LG0l modes of radial and azimuthal polarisation states, respectively.
Prof Andrew Forbes, email@example.com, CSIR