Nonreciprocal optical nonlinear metasurfaces

We demonstrate nonreciprocal one-way transmission through a half-a-micron-thick nonlinear silicon-VO2 metasurface for low-power CW excitation. Reciprocity is broken by optically self-induced phase transition of VO2 occurring at different intensities for the opposite directions of illumination

Enhanced five-photon photoluminescence in subwavelength AlGaAs resonators

Multiphoton processes of absorption photoluminescence have enabled a wide range of applications including three-dimensional microfabrication, data storage, and biological imaging. While the applications of two-photon and three-photon absorption and luminescence have matured considerably, higher-order photoluminescence processes remain more challenging to study due to their lower efficiency, particularly in subwavelength systems. Here we report the observation of it five-photon luminescence from a single subwavelength nanoantenna at room temperature enabled by the Mie resonances. We excite an AlGaAs resonator at around 3.6 um and observe photoluminescence at around 740 nm. We show that the interplay of the Mie multipolar modes at the subwavelength scale can enhance the efficiency of the five-photon luminescence by at least four orders of magnitude, being limited only by sensitivity of our detector. Our work paves the way towards applications of higher-order multiphoton processes at the subwavelength scales enabled by the physics of Mie resonances.Comment: 18 pages, 5 figure

The state of the Martian climate

60°N was +2.0°C, relative to the 1981–2010 average value (Fig. 5.1). This marks a new high for the record. The average annual surface air temperature (SAT) anomaly for 2016 for land stations north of starting in 1900, and is a significant increase over the previous highest value of +1.2°C, which was observed in 2007, 2011, and 2015. Average global annual temperatures also showed record values in 2015 and 2016. Currently, the Arctic is warming at more than twice the rate of lower latitudes

Optical metamaterials with quasicrystalline symmetry: symmetry-induced optical isotropy

We compare, both experimentally and theoretically, metamaterials with three different symmetries: square lattice, hexagonal lattice, and quasicrystalline Penrose tiling. By relying on an advanced Jones calculus, we link the symmetry properties to the farfield optical response, such as ellipticity and circular dichroism, as the incident angle is varied. We show that hexagonal lattice metamaterials, when compared to the square ones, exhibit less circular dichroism and ellipticity due to their higher symmetry. Furthermore, we show that in contrast to periodic metamaterials, quasicrystalline metamaterials inhibit ellipticity and circular dichroism and open a new route to isotropy in metamaterials at oblique incidence

Nonlinear coupled-mode theory for periodic plasmonic waveguides and metamaterials with loss and gain

We derive general coupled-mode equations describing the nonlinear interaction of electromagnetic modes in periodic media with loss and gain. Our approach is rigorously based on the Lorentz reciprocity theorem, and it can be applied to a broad range of metal-dielectric photonic structures, including plasmonic waveguides and metamaterials. We verify that our general results agree with the previous analysis of particular cases, and predict novel effects on self- and cross-phase modulation in multilayer nonlinear fishnet metamaterials.We acknowledge support from the Australian Research Council including Future Fellowship FT100100160 and Discovery Project DP130100135, and Australian NCI National Facility