Optical plasmonics
For more than a century, metallic nanoparticles have been known to display fascinating optical properties related to the excitation of size-dependent resonances. These resonances are now known as Localized Surface Plasmon Resonances (LSPRs), and they are the result of the coherent oscillation of free electrons in the metal driven by the electric field of light. The properties of LSPRs generally depend on the particle's size, shape, material composition, surrounding medium, and light polarization. Until recently, studies on these properties were mostly descriptive in nature. However, advances in nanofabrication techniques have allowed the structuring of metals in a length scale which was previously inaccessible. With nanoscale structural precision, metallic particles may be tailored to convert free space optical radiation into localized energy and viceversa, thereby functioning as antennas for light. Both the local field enhancement and the far-field scattering can be controlled with nanoantennas, and if an emitter is placed in their proximity, the emission properties can be very drastically modified. These remarkable features have led to a massive revival of metallic nano-optics, in which research has shifted from a descriptive to a creative state. That is, the optical properties of metallic nanostructures are no longer passively studied, but actively designed to sustain a desired effect.
In the group Surface Photonics, we create and investigate complex metallic nanostructures sustaining novel effects of both fundamental and applied interest. These effects are finding their application in the lighting and sensing industries, which may benefit from the designed density of optical states that metallic nanostructures can offer.
Lighting
Approximately 7% of the world's total energy consumption is devoted to the generation of light. In traditional light sources such as incandescent lamps, about 90 % of the energy used is wasted producing heat. Fluorescent lamps are about four times more energy efficient, but still, a significant fraction of the energy is wasted. Solid state lighting technology, i.e., organic and inorganic Light Emitting Diodes (LEDs), has emerged as a viable technology for the efficient generation of light. Improving the performance of LEDs is therefore of central industrial and social relevance, and researchers across the world are actively pursuing alternative paths to this end.
In the Surface Photonics group, we investigate the light emission from quantum dots or dyes when these are coupled to plasmonic structures. We study light-matter interactions at the nanoscale, including the numerous resonant modes that can be excited in metallic nanostructures, and their possible implementation for enhancing the performance of LEDs.
Plasmonic sensors
The same principles by which optical antennas can modify light emission, allow them to achieve the complementary effect, i.e., modify the optical extinction. The latter has important implications for sensing, where low-cost, compact, robust, and highly sensitive devices are increasingly needed. In the Surface Photonics group, we investigate plasmonic sensors for a sensitive detection of gas.
