Our research group has a strong background in radiofrequency and integrated optics for optical communications. We specialize in high performance components for the silicon and indium phosphide platforms, with applications to high speed telecom receivers. We apply this extensive knowledge to novel photonic sensing techniques, based on the interaction of the evanescent field of a waveguide mode with an analyte deposited on the waveguide surface. This technique enables sensitivities on par with surface plasmon resonance (SPR), but with the potential of multiplexing tens or hundreds of different test on a single chip.

Research lines

Highly sensitive integrated photonic biosensors

Based on our expertise on coherent (amplitude and phase) optical phase detection techniques for optical communications we develop highly sensitive evanescent field optical biosensors. These sensors aim to: a) detect very low concentrations of drugs and pathogens and b) monitor molecular reactions in real-time for early diagnosis of diseases and drug discovery. The key advantage of photonic biosensors is that they enable label-free monitoring and detection, obviating intermediate labelling steps that can hamper detection reliability. Photonic biosensors based on integrated optics can be fabricated on a large scale, and, as opposed to surface plasmon resonance, their sensitivity is not limited by reduced propagation distances. The Silicon-on-Insulator platform offers increased sensitivity for evanescent field sensors, and a high degree of miniaturization and integration, enabling parallelized probing. Parallelization allows for several different reactions to be monitored simultaneously, while at the same time performing redundancy checks to reduce false positive/negatives. We are currently working with colleagues from the Catalan Institute of Nanoscience in Barcelona to test these our sensor designs.

Nanostructured metamaterial waveguide components

All-dielectric waveguides segmented at a sub-wavelength scale suppress diffraction effects, and behave as equivalent homogenous metamaterials whose refractive index and other optical properties can be engineered. This enables the design of photonic components with unprecedented performance, for applications in both (bio)sensing and communications. Our group has developed in-house simulation tools for these structures and has pioneered, together with our colleagues from the National Research Council of Canada, a variety of high performance devices, ranging from high efficiency grating couplers, to ultra-broadband waveguide couplers and high-sensitivity photonic biosensors.

Integrated photonic waveguides and components for the mid-infrared

The mid-infrared (MIR) wavelength region (2-20 micrometers) is key for spectroscopic sensing because many compounds of interest (e.g. Methane, Carbon monoxide, Benzene) exhibit specific absorption spectra (“fingerprints”) in this region. With applications ranging from explosive detections to medical diagnosis the marked for MIR sensor is expected to reach $7 billion by 2019. Integrated photonic devices operating in the MIR hold potential for measurement equipment with higher performance and reliability, while reducing size, weight and cost. We work with colleagues from the Optoelectronics Research Center at Southampton University to develop waveguides and devices that will enable photonic sensors in this fingerprint region.

Optical coherent sensors with phase and polarization diversity

We continue to push the envelope of telecom optical receivers, advancing in the complete monolithical integration of these devices, with a particular focus on polarization control. This concept, which is of fundamental importance in optical communications, has not yet been widely explored for integrated sensing, where it has the potential to provide further enhancements in sensitivity and selectivity.

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