In the September 2017 issue of Nature Photonics, Dr A. Rahman and Professor P. Barker from Physics and Astronomy at UCL report on the first demonstration of optical refrigeration of a submicrometre particle suspended by laser light. The tiny levitated cryostat, consists of a single nanocrystal of Yb3+:YLF crystal cooled to temperatures as cold as −143 °C by illuminating, trapping and aligning it with a single laser beam. Their work has shown that the internal temperature of the nanocrystal can be controlled over a wide range using different trapping laser wavelengths. The laser polarization controls the orientation of the trapped crystal and maximizes its cooling. This development is a further important step towards bringing these macroscopic systems into the quantum regime.
Citation: Laser refrigeration, alignment and rotation of levitated Yb3+:YLF nanocrystals, A.T.M. Anishur Rahman and P. F. Barker, Nature Phonics, Nature Photonics 11, 634–638 (2017)
Congratulations to Lia (Ying Lia Li) for passing her Ph.D. viva on the 22nd September! Her Ph.D. thesis is titled ‘Cooling and sensing using whispering gallery mode resonators’.
Our paper on using optical whispering gallery modes (WGM) to detect and cool mechanical modes of a microsphere-cantilever and the motion of the tapered fibre used to couple light into the WGM has been published in Optics Express!