In a paper published in Appl. Phys. Lett., we report the first measurements of optothermal nonlinearity of silica aerogels. Silica based aerogels are ultra porous materials with refractive index close to unity. Their extreme porosity is responsible for very low thermal conductivity, which in turn leads to very peculiar optothermal properties. In this paper, in collaboration with researchers at the University Sapienza and CNR, we measured the optothermal nonlinear coefficient of silica based aerogels in the visible range. The full article can be found here.
In a paper published in Phys. Rev. Lett., we experimentally demonstrate that the distribution of phase singularities in vectorial random light fields is anisotropic. Our collaborators at AMOLF, led by Prof. Kobus Kuipers, have measured the distribution of phase singularities supported by a chaotic electromagnetic landscape, reading the surface of a photonic crystal (PhC) cavity with a SNOM. PhC chaotic resonators in silicon on insulator technology are an ideal platform to prepare a random field with repeatable and well defined characteristics. Exploiting this feature, we were able to track the deep-subwavelength phase singularities supported in the cavity. Our results demonstrate that, due to the… Read More »Spatial Distribution of Phase Singularities in Optical Random Vector Waves
Our work on the “Optically Induced Metal-to-Dielectric Transition in Epsilon-Near-Zero Metamaterials” has recently appeared in Scientific Reports. In this work we designed a metamaterial with epsilon-near-zero (ENZ) response, that is tuned all-optically from a metallic to dielectric behaviour. The transition is demonstrated using an ultrafast pump and probe scheme. The study unveils both analytically and experimentally the full associated nonlinear dynamics. The full article can be found here.
In collaboration with Heriot-Watt University and Purdue University, we published a paper in Phys. Rev. Lett. demonstrating that epsilon-near-zero metamaterials (ENZ) exhibit an enhanced nonlinear response. In this study we demonstrated a six-fold enhancement of the Kerr nonlinear refractive index in proximity of the ENZ condition, in the near-infrared. The experiemtn was performed on Al-doped ZnO (AZO) thin film, and demonstrates a general behaviour of ENZ materials. The full paper can be found here.
In this work, published in Laser Photonics Review we report on the all-optical control of chaotic optical resonators based on a silicon on insulator (SOI) platform. We show that simple non-chaotic cavities can be tuned to exhibit chaotic behaviour via intense optical pumping, inducing a local change of refractive index. To this extent we have fabricated a number of devices and demonstrated experimentally and theoretically that chaos can be triggered on demand on an optical chip. We show that the degree of chaos supported by a microcavity can be controlled dynamically using light itself. We start with a square (non-chaotic) cavity obtained on SOI.… Read More »Ultrafast All-Optical Order-to-Chaos Transition in Silicon Photonic Crystal Chips
Congratulations to James, who has won the runner up prize for the Poster competition at the 12th International Symposium on Photonic and Electromagnetic Crystal Structures (PECS-XII), taking place at University of York in July 2016. His Poster on “Flexible Broadband Metasurface Holograms” was chosen by a panel of judges from a selection of nearly 40 participating entries.
Congratulations to Aline for winning the Arthur Maitland prize for best talk in this year’s PhD assessments. Aline’s PhD thesis focuses on novel materials for advanced plasmonics applications.
Congratulations to Eilidh Johnston, who has been declared the overall winner of the undergraduate awards 2015, in the category of Physics and Mathematics. Eilidh’s recently completed her MSc thesis in our group with a project on ‘DNA Assisted Fabrication of 3D Metamaterials’, in collaboration with the groups of Dr Carlos Penedo and Dr Euan Kay.
Congratulations are in order for Peter Reader-Harris, who passed his PhD viva in August. Peter was the first PhD student to join the Synthetic Optics group and everyone here is sad to see him go. It’s been really, really, really, good.
In a paper published in Physical Review Letters we demonstrate that a one-dimensional stack of achiral material can exhibit electromagnetic chirality… Artificial chirality is currently a very much-researched field both from a fundamental point of view and for its applications in molecular biology, life science, optics, crystallography and particle physics. In this context, plasmonic-based metamaterials are the natural platform of choice because their smallest constituents (meta-atoms) can be engineered to exhibit artificial chirality. This is usually achieved by breaking the spatial symmetry of the meta-atoms, structuring plasmonic materials at the nanoscale, either in 3D (akin to natural chirality) or in 2D, but never in 1D. Here… Read More »Chiral Epsilon-Near-Zero Metamaterials