A Nonlinear plasmonic antenna switch as building block for ultracompact photonic devices **CLOSED**

Active control over light on nanometer length scales holds promise for many applications in modern science and technology, ranging from optical telecommunication to coherent quantum information. In this First Grant we will develop a new class of ultracompact photonic devices based on nanoscale plasmonic antennas. Plasmonics, the science dealing with confining light at the surface of metals, has the potential to become one of the key nanotechnologies capable of combining electric and photonic components on a single chip. Photonic integration is important to achieve medium-range information transfer and chip-to-chip interconnects in next-generation communication networks.Analogous to their radiowave counterparts, plasmonic nanoantennas are ideal structures for matching incident optical radiation to a nanoscale volume. We propose that the small footprint and ultrafast response of a single antenna can be used to design a new type of ultrafast optical transistor. We introduce here a novel design of an antenna optical switch capable of producing a large modulation depth and requiring only a fraction of the optical power used in state-of-the-art microphotonic switches. In the first part of the project we will demonstrate the proof-of-principle of antenna switching. In the second part, we will integrate a nanoantenna onto a silicon photonic waveguide. We will use the antenna to control the transmission of the photonic waveguide using its very strong scattering at the resonant plasmon wavelength. During our experiments we will work together with a UK fiber-laser company in optimizing a new light source for single-nanoantenna ultrafast spectroscopy.As a follow-on to this project, we will explore the use of antenna switches as saturable absorber medium in a novel class of ultrafast semiconductor lasers. For this we build on the very strong expertise already present in Southampton on semiconductor lasers. The proposed research programme will combine fundamental scientific research with novel technological applications, bringing together yet unconnected fields of research. Successes will benefit to a new generation of light-driven information technology and to low-cost ultrafast lasers for use in applications like biosensing and terahertz generation. Although the initial research will be at a fundamental level, its results will have a large application perspective, with potential benefits to the UK photonics industry.