Light unlimted - active and passive exploitation of light at the nanometre scale

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Light and the various ways it interacts with matter is our primary means of sensing the world around us. It is therefore no surprise that many technologies are based on light; for example submarine optical fibres make up the backbone of the Internet and display technology delivers affordable and compact crystal clear televisions. However, light itself has a limitation that we are still trying to overcome: light cannot be imaged or focused below half its wavelength, known as the diffraction limit . To see smaller objects we must use shorter wavelengths. e.g. Blue-ray, uses blue lasers (405 nm) to store more information than DVDs, which use longer wavelength red lasers (650 nm). Today, we are learning to overcome this limit by incorporating metals in optical devices. The proposed research investigates the use of metals to shatter the diffraction limit for creating new technological products, expand the capabilities of computers and the internet and deliver new sensor technologies for healthcare, defense and security.We often take for granted just how strongly light can interact with metals. Electricity, oscillating at 50 Hz (essentially very low frequency light), has a wavelength of thousands of kilometers, yet a wall-plug is no larger than a couple of inches; well below the diffraction limit! The relatively new capability to structure metal surfaces on the nanoscale now allows us to use this same phenomenon to beat the diffraction limit in the visible spectrum. Metals do this by storing energy on the electrons that collectively move in unison with light, called surface plasmons. This approach has recently re-invigorated the study of optics at the nano-scale, feeding the trend to smaller and more compact technologies.So what sets nano-optics aside from low frequency electricity if they share the same physics? I believe the paradigm of nano-optics is the capability to reduce the size of visible and infrared light so that it can occupy the same nano-scale volume as molecular, solid state and atomic electronic states for the first time. Under natural conditions the mismatch makes light-matter interactions inherently weak and slow. With nano-optics, interactions not only become stronger and faster but weak effects once difficult to detect are dramatically enhanced. This goal of this proposal is to strengthen such weak effects and utilize them to realize new capabilities in optics.With any new type of control come caveats. Firstly, it is difficult to focus light from its normal size beyond the diffraction limit. Secondly, having overcome the first challenge, light on metal surfaces is short lived due to a metal's resistance. My research plan is geared to directly address these challenges. The first thrust develops a concept that I recently proposed to mitigate the problem of energy loss to the point where surface plasmons become useful. Building on Silicon Photonics, a well-established commercial optical communications architecture, I can use established techniques to seamlessly transfer light between the realms of conventional and nano-optics with the potential for short term impact on photonics technology. The second thrust exploits my recent breakthrough on surface plasmon lasers, which can generate light directly on the nano-scale and sustain it indefinitely by laser action. This overcomes both challenges in nano-optics simultaneously. While conventional lasers transmit light over large distances, it is the light inside surface plasmon lasers that is unique. I want to use this light for spectroscopy at single molecule sensitivities. Just as ultra-fast lasers, serving as scientists' camera flash, have given us snap shots of Nature's fleeting processes, so surface plasmon lasers will allow us to probe Nature with unprecedented resolution and control at the scale of individual molecules. Exploring optics at untouched length scales is an exciting opportunity giving us the potential to make fundamentally new discoveries.