Postdoctoral Research Fellow - Australian Attosecond Science Facility, Griffith University
The experiment that I conducted at the Australian Attosecond Science Facility during my postdoc utilised an ultra-fast laser with a Ti-sapphire oscillator, amplifier and hollow-fibre wave-guide to produce carrier-envelope phase (CEP) stabilised pulses at 5.5 fs. This corresponds to only a few oscillations of the electric field. This system uses an f-2f interferometer to lock the peak of the 800nm carrier signal to the pulse envelope.
When this laser is focussed, it possesses enough intensity (~1x10^15 Wcm^2) to ionise gas atoms in a gas jet. The electron is liberated at the peak of the electric field of the carrier wave and accelerated away from the ion by the field. When the direction of the field changes, the electron is returned to the ion and an extreme ultraviolet (XUV) photon is released upon collision in the direction of the laser beam.
This process is called high-harmonic generation (HHG). The XUV spectrum consists of odd harmonics of the carrier frequency and ends in a high energy region called the cut-off. Evidence for isolated attosecond pulses can be observed as a flattening of the spectrum in the cut-off and occurs at extremely stable CEP of zero phase.
The experiment used HHG generated from two gas jets placed in the laser beam. A jet was placed at the laser focus and a translatable jet could be moved from the focus back towards the laser source. XUV produced in the jets was found to interfere coherently. Overlapping jets produced constructive interference and jet separation produced destructive interference until at a revival distance, the constructive interference was reproduced. This lead to a new interferometer with zeptosecond timing jitter.
Doctor of Philosophy (Ph.D.), Physics - Griffith University
I completed a PhD in Physics at Griffith University in April 2011. My thesis was concerned with novel lithographic fabrication of nanostructures and surface analysis of these structures. I published 4 papers from my thesis work and one reviewer described my thesis as “an outstanding contribution to the field of atom lithography”. This work required optical enhancement of an atomic beam and involved many optical engineering techniques including the optimisation of transmission in optic fibres.