Enhanced blue light generation in Rb vapour
Team
Andrew Daffurn
PhD student
Dr Aidan Arnold
Reader
Dr Rachel Offer
Researcher
Prof Erling Riis
Professor
Prof Paul Griffin
Professor
Prof Sonja Franke-Arnold
Professor
In this Strathclyde/Glasgow collaboration we have observed highly efficient generation of 420 nm laser light via up-conversion of near-infrared lasers in a hot rubidium vapor cell, with single-pass conversion efficiency of 260%/W, significantly higher than in previous experiments. Favorable scaling of our current 1mW blue beam power with additional pump power has been shown. We have investigated:
- the power-, polarisation-, frequency-, temperature-efficiency, of the four-wave mixing processn
- trans-spectral orbital angular momentum (OAM) transfer, utilising optimised spatial light-modulator (SLM) patternsn
- the best holograms on spatial light modulators (SLMs) for making OAM modes
- spectral narrowing and further enhancement of efficiency via the use of a ring cavity around the Rb cell
- the quantitative OAM distribution of the generated light and inferred spiral bandwidth
Relevant Rb energy levels for the
four-wave mixing process.
1mW of 420nm light from ~20+20mW of focused 780nm and 776nm light.
420nm beam power with (blue, 1MHz linewidth) and without (red) a ring cavity.
Experimental image of a 420nm laser beam carrying
trans-spectral OAM transferred from the near-infrared pump beams.
Quantitative information on the OAM is found by using Fourier methods
on the interferogram formed when the beam is overlapped with its mirror image.
Funding
