Cooperative Energy Transfer Controls the Spontaneous Emission Rate Beyond Field Enhancement Limits.

Quantum emitters located in proximity to a metal nanostructure individually transfer their energy via near-field excitation of surface plasmons. The energy transfer process increases the spontaneous emission (SE) rate due to plasmon-enhanced local field. Here, we demonstrate a significant acceleration of the quantum emitter SE rate in a plasmonic nanocavity due to cooperative energy transfer (CET) from plasmon-correlated emitters.

Scanning Probe Photonic Nanojet Lithography.

The use of nano/microspheres or beads for optical nanolithography is a consolidated technique for achieving subwavelength structures using a cost-effective approach; this method exploits the capability of the beads to focus electromagnetic waves into subwavelength beams called photonic nanojets, which are used to expose the photoresist on which the beads are placed. However, this technique has only been used to produce regular patterns based on the spatial arrangement of the beads on the substrate, thus considerably limiting the pool of applications. Here, we present a novel microsphere-based optical lithography technique that offers high subwavelength resolution and the possibility of generating any arbitrary pattern.

Hybrid plasmonic-photonic whispering gallery mode resonators for sensing: a critical review.

In this review we present the state of the art and the most recent advances in the field of optical sensing with hybrid plasmonic-photonic whispering gallery mode (WGM) resonators. After a brief introduction on the basic physics behind photonic WGM resonators and localized surface plasmon (LSP) nanostructures, we analyze the different types of optical sensors specifically designed for bulk refractive index sensing, molecular binding and single object detection. We point out the physical and technological key points of the different approaches proposed in the literature, and we systematically compare hybrid sensors and purely photonic WGM sensors.

3D coaxial out-of-plane metallic antennas for filtering and multi-spectral imaging in the infrared range.

We fabricated and investigated a new configuration of 3D coaxial metallic antennas working in the infrared which combines the strong lateral light scattering of vertical plasmonic structures with the selective spectral transmission of 2D arrays of coaxial apertures. The coaxial structures are fabricated with a top-down method based on a template of hollow 3D antennas. Each antenna has a multilayer radial structure consisting of dielectric and metallic materials not achievable in a 2D configuration.

Broadband absorption enhancement in plasmonic nanoshells-based ultrathin microcrystalline-Si solar cells.

With the objective to conceive a plasmonic solar cell with enhanced photocurrent, we investigate the role of plasmonic nanoshells, embedded within a ultrathin microcrystalline silicon solar cell, in enhancing broadband light trapping capability of the cell and, at the same time, to reduce the parasitic loss. The thickness of the considered microcrystalline silicon (μc-Si) layer is only ~1/6 of conventional μc-Si based solar cells while the plasmonic nanoshells are formed by a combination of silica and gold, respectively core and shell. We analyze the cell optical response by varying both the geometrical and optical parameters of the overall device.

Optimising apodized grating couplers in a pure SOI platform to -0.5 dB coupling efficiency.

We present a theoretical optimisation of 1D apodized grating couplers in a "pure" Silicon-On-Insulator (SOI) architecture, i.e. without any bottom reflector element, by means of a general mutative method.

How to assess light trapping structures versus a Lambertian Scatterer for solar cells?

We propose a new figure of merit to assess the performance of light trapping nanostructures for solar cells, which we call the light trapping efficiency (LTE). The LTE has a target value of unity to represent the performance of an ideal Lambertian scatterer, although this is not an absolute limit but rather a benchmark value. Since the LTE aims to assess the nanostructure itself, it is, in principle, independent of the material, fabrication method or technology used.

Photonic light-trapping versus Lambertian limits in thin film silicon solar cells with 1D and 2D periodic patterns.

We theoretically investigate the light-trapping properties of one- and two-dimensional periodic patterns etched on the front surface of c-Si and a-Si thin film solar cells with a silver back reflector and an anti-reflection coating. For each active material and configuration, absorbance A and short-circuit current density Jsc are calculated by means of rigorous coupled wave analysis (RCWA), for different active materials thicknesses in the range of interest of thin film solar cells and in a wide range of geometrical parameters. The results are then compared with Lambertian limits to light-trapping for the case of zero absorption and for the general case of finite absorption in the active material.