A nonlinear plasmonic antenna switch as building block for ultracompact photonic devices.

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.

The research presented in this proposal is aimed at integration of plasmonic nanoantennas in new technologically important areas such as silicon photonics and ultrafast semiconductor lasers. The work package combines fundamental research with a strong application perspective. We expect this approach to generate considerable impact in society, which will be actively pursued in various strong collaborations planned in this project. Both the areas of plasmonics and microphotonics have a considerable demonstrated positive impact on society. Examples that have improved the quality of life are plasmonic biosensors used in clinical environments and optical telecommunication which has powered broadband data-communication and internet. The unique features of the proposed nanoantenna switches will allow the design of novel nanoscale optical devices. In particular, we will explore the use of antennas to control the flow of light in silicon integrated photonic circuits. Silicon photonics holds enormous technological potential as a novel platform for optical information technology. It is expected to result in new and improved functionalities compared to existing fiber communication technology. Development of silicon photonics has a large industrial support base worldwide including Intel, IBM, Kotura, and in the UK, Bookham and QinetQ. Our programme on nanoantennas has the potential to contribute to establishing a toolkit of components for a viable silicon photonics technology. Antenna switches specifically can be applicable as broadband directional couplers, ultrafast broadband switches, and tunable frequency filters.In the follow-up research we will investigate the functionality of antenna switches as saturable absorber in ultrafast semiconductor lasers. This research will have very important potential applications; a low-cost compact femtosecond laser would be of great benefit for many applications of ultrafast technology, including compact biomedical sensors and terahertz generation for security applications. In the transfer of our results, we will be able to benefit from the excellent connections with relevant industrial and scientific beneficiaries already available in the groups of Prof. Reed and Prof. Tropper. As an example of our commitment in actively seeking interaction with industry we emphasize the collaboration with small-scale technology company Fianium in this project. The integrated fiber solution which we will develop as part of our project may find practical use for example in biomedical imaging and nondestructive materials testing. Impact in the academic environment will primarily take place through scientific publications and presentations at national and international scientific meetings. Integration of antennas with silicon photonics will contribute to a relatively young research area where very little explorations have been made so far. Successes in integrating these research areas will lead to a strong synergy and increased momentum. The collaboration between the PI and the Silicon Photonics team lead by Prof. Reed will be able to gain visibility in the community as Prof. Reed is currently leading a large UK-wide consortium. Impact on people will take place through the PI's interactions with PhD and undergraduate students based on his position as a lecturer. Although no graduate student is directly associated to this research project, members of the PI's research team will be able to benefit from its progress, through interactions in the lab and during work discussions. Final-year undergraduate (MPhys) students will be working along with the PI's research team as part of their educational training. Other contributions to student education are made in the form of summer studentships, for which the PI has already secured two bursaries for the year 2009.