In this article we design and fabricate an anti-reflection layer for a multilayer epsilon-near-zero metamaterials. The layer is designed using a Multi-Objective-Grey-Wolf-Optimizer (MOGWO), using the same constituent materials of the ENZ stack. The anti-reflection layer yields a transmission enhancement of 20% over a 150 nm range and reflection minimization of 50% over a 200 nm range, respect to the uncoated sample.
In this paper, we demonstrate the all-optical manipulation of polymeric membranes in microfluidic environments. The membranes are decorated with handles for their use in holographic optical tweezers systems. Our results show that due to their form factor the membranes present a substantial increase in their mechanical stability, respect to micrometric dielectric particles. This intrinsic superior stability is expected to improve profoundly a wide range of bio-photonic applications that rely on the optical manipulation of micrometric objects.
In a paper published in Nature Communications, we report on the integration of sub-micron semiconductor lasers in living cells. In this work, fruit of the collaboration with Malte Gather and his group at the University of St Andrews, we demonstrate that lasers with dimensions much smaller than that of many cell nuclei can be used to tag individual cells and sense their environment. This research paves the way for a new bio-photonics platform that will provide new insight into cell biology, including research in immune cells, neutrons and cancer cells. A. H. Fikouras, M. Schubert, M. Karl, J. D. Kumar, S. J. Powis, A. Di… Read More »Integration of sub-micron semiconductor lasers in living cells
In a paper published in APL Photonics we demonstrate the control of the emission of a GaAs quantum dot (QD) embedded in a GaAs/AlGaAs nanowire (NW) by the post-fabrication of a plasmonic grating on its surface. We fabricated a sub-wavelength Pt grating directly on the NW surface, via electron beam induced deposition, to enhance the emission efficiency of QD for the polarization parallel to the NW of 45%, with a 17% reduction in the photon lifetime. These findings and EBID approach offer great opportunities for the development of nanopatterned QD emitters and new hybrid nanophotonic platforms for efficient single photon sources.
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.