Welcome to Queen's Ultrafast
To observe very fast dynamics, one needs a camera that can capture the action in freeze-frame. The fastest event controllable by man is the optical pulse. Beams of light with pulse durations of 100 fs or shorter can be routinely generated allowing the dynamics of chemical reactions, molecular motion, or other ultrafast processes to be followed in quasi real-time. Recall that 1 fs is one millionth of a nanosecond, so in comparison, our common understanding of fast is glacial.
Research in ultrafast is truly cross-disciplinary since ultrafast processes are relevant in a wide range of fields, from semiconductor technology to bioprotein functionality. A key focus of our research is into the ultrafast of the ultrasmall. Man-made nanostructures provide a fascinating playground into the laws of quantum mechanics. Being small provides a complete new functionality and generates new applications all through novel ultrafast dynamics.
Short optical pulses are produced by compressing a submicrosecond duration pulse into 100 femtoseconds. That corresponds to an intensity increase greater than one million. Also, since the optical source is a laser, all the energy can be focused into a spot size comparable to the wavelength of light. The result is a beam with an intensity measured in TW/cm2. Such an intense beam seriously perturbs any matter it interacts with, moving our exploration into the nonlinear regime. We now have access to excited states of the system, can read out novel information about system symmetry, and can bridge transitions that normally would be forbidden. We can control the system in novel and often counter-intuitive ways, and read out information from the system that would normally remain hidden. With light intensities sufficiently high, we can even ablate and "cut" the material with our optical pulse. Combining imaging with micromachining opens up a new perspective into extreme light-matter interaction, and has important technological implications.