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My research is concerned with the interaction between light and artificially structured materials and finds application in both telecommunications and biosensing. The recognition that light will be diffracted by small-scale structures goes back hundreds of years, but applications and new understandings continue to emerge today. At present we are focusing on the following research topics:

1. Slab waveguide optical demultiplexers and switches: We are investigating a variety of devices in slab waveguides, in which light is confined in the vertical direction but can propagate freely in the other two dimensions. It can thus be thought of as ‘flat’ free-space optics, into which we are integrating many different structures. These can combine the characteristics of both free-space and guided wave devices. Examples include photonic crystal superprism demultiplexers, distributed etched grating demultiplexers and electro-optic switches, fabricated in silicon-on-insulator and GaAs. These devices are intended for next-generation agile all-optical networks.

2. Vertical integration strategies for photonic systems: We are investigating techniques to stack different optical materials and devices vertically, in order to integrate different materials and devices together more effectively. The key challenge here is to develop compact vertical interconnects (the equivalent of vias in microelectronics) that are also efficient. The eventual goal is to integrate active devices (lasers, amplifiers and detectors) with passive optical waveguides, with application in chip-to-chip interconnects.

3. Surface plasmon resonance biosensors: Surface plasmon resonance (SPR) is a widely used affinity biosensing technique. We are attempting to increase the sensitivity of SPR sensors, both through the use of metallic optical nanostructures and also by spatially selective surface chemistry. We are working closely with researchers in medical departments in order to target the detection of particular biomarkers.