Visit to NanoSoft Lab, IPCF-CNR (Messina)

Phil is spending the week of 07-11 November visiting Onofrio Marago and colleagues at the NanoSoft Lab, IPCF-CNR (Messina).  Our groups have a long-running collaboration, and exchange visits are funded by the Royal Society as part of our International Joint Project on Photonic Force Microscopy.

Physics Department Colloquium

Dr Gavin Crooks (Lawrence Berkeley National Laboratory, University of California Berkeley) will be giving this term's Departmental Colloquium today, Wed 19 Oct, on Statistical Thermodynamics and the Breaking of Time Symmetry.

Abstract: The irreversible dissipation of energy is directly related to the breaking of time reversal symmetry. I will discuss some of the implication of these phenomena to microscopic, driven non-equilibrium systems, such as single molecular force-extension experiments, biological molecular motors and artificial photosynthesis.

Departmental Teaching Prize

Phil has won the Department of Physics and Astronmy's Departmental Teaching Prize for 2011.  In 2010-11 Phil was lecturing the course Lasers & Modern Optics (PHAS3443) for third and fourth year undergraduates.  The prize-giving ceremony will be held on Friday 28 October.  Earlier this year Phil also won the Mathematical and Physical Sciences (MAPS) Faculty Teaching Award.

New Group Members

Kelly Thorneycroft has joined the UCL Optical Tweezers Group for her MSci project.  Kelly is a fourth year undergraduate studying Natural Sciences and will be working on optical trapping and binding experiments and biophysical applications.

Electromagnetic and Light Scattering XIII

The latest conference in the series 'Electromagnetic and Light Scattering' (ELS XIII) is being held in Taormina, Sicily from 26-20 September.

Phil will be giving an invited talk about the UCL Optical Tweezers Group's research on Optical Trapping and Optical Binding Using Cylindrical Vector Beams.  The book of extended abstracts of all the conference presentations is published in a special issue of Atti della Accademia Peloritana dei Pericolanti Volume 89, Supplement No. 1 (2011).

Fano-Doppler Cooling paper

Our paper 'Fano-Doppler laser cooling of hybrid nanostructures' is now published in ACS Nano 5 7354-7361 (2011).

Laser cooling the center-of-mass motion of systems that exhibit Fano resonances is discussed. We find that cooling occurs for red or blue detuning of the laser frequency from resonance depending on the Fano factor associated with the resonance. The combination of the Doppler effect with the radiation cross-section quenching typical of quantum interference yields temperatures below the conventional Doppler limit. This scheme opens perspectives for controlling the motion of mesoscopic systems such as hybrid nanostructures at the quantum regime and the exploration of motional nonclassical states at the nanoscale.

Nuffield Bursary Update (3)

Throughout the course of her Nuffield Foundation project this summer Ewa Karczewska will be making updates of her progress on our blog.  Her final instalment is below.

Ewa writes: During the 8-week project with the UCL Optical Tweezers Group I have learnt a great deal about the laboratory work as well as the current experiments run in it, which focus on the evanescent field and the micro- and nano- structures trapping. I have also gain knowledge about the evanescent wave and the different optical fibre modes.
My research was focused on the thin fibre fabrication using the “heating and pulling”method. The light (λ = 1064nm) was coupled to the tapered fibre so that the evanescent field near the taper region was created. That field was then tested with the micro-sized spheres. When the field was strong enough and the surface of the fibre was smooth enough, the spheres were observed to move along the fibre along the direction of the light propagation.
Overall, I have managed to obtain an efficient method of obtaining thin (about 1.5μm in diameter) optical fibres using the “heating and pulling” method and observe the spheres of 2μm to move along the fibre once the laser light was coupled through it. When the laser light was coupled from both sides of the fibre I could move the spheres in two directions and also balanced the two beams so that the spheres stayed in place.
I have also investigated the behaviour of the micron-sized spheres when the polarisation of the trapping light of an optical tweezers was changed from linear to circular polarisation as well as from radial to azimuthal polarisation.
That project gave me a valuable experience and a great insight into the research work, which will be very useful in my future study for PhD.

From September Ewa will be studying for the third year of her degree as a year abroad in Toronto University.