A very large range of experiments to better understand and control the confinement of light on the nm and sub-nm scales has been undertaken. Our approach to making scalable precision nano-architectures that confine light has been using bottom-up self-assembly of nanostructures, and this has gained international notoriety as a highly-effective route that avoids expensive complex fabrication. We routinely now make nm-gap structures that confine light (daily), and explore their properties. This underpins all our research.
We have published >50 high impact papers since the start of the project, so that we can only highlight a few of the key results here.
(note that the publications upload page is not working [email with ERCEA Scientific Follow-Up Team 7/7/23] and thus a pdf of the list has been provided to the project officers).
Most significant for the project is our quantification of optical-induced forces on molecules inside metallic nanogaps, which shows they are a thousand times larger than expected from classical theory. This arises from the interaction between light, polarisable molecules, and metallic surfaces. We have produced an initial model that explains this, and theory group around the world are struggling to develop this. The key issue is to combine quantum and classical theories, which is currently impossible. However our experiments are unambiguous, rich and extensive, and constrain many explanations. We even now develop cases where room light can move around the metal atoms from these forces, or a single dye molecule can resculpt metal contacts when illuminated.
A second significant advance has been to show that mid-infrared light can also be confined in our nanogap cavities, which allows new phenomena to be demonstrated. In particular we invented (and patented) a new way to use this to detect midinfrared light by ‘upconverting’ it into visible light inside these nanogaps. We are now trying to understand the key mechanisms which involve interactions with the confined molecules and the midinfrared and visible light, and also make a demonstrator.
A third advance has been to show that illuminating molecules inside these nanogaps can change their bonds, weakening their strength progressively as the light becomes more intense. We have also developed a theory based on ‘optomechanics’ that explains this, and see it as changes in the vibrational spectrum for even weak light intensities.
Finally we also developed a system combining carbon nanotubes and thermoresponsive polymers to make microscale ‘jellyfish’ that flap their tentacles when illuminated by light, and we are continuing to develop these actuators.
