Nonlinear optics describes many interactions where the intensity of the optical wave changes the optical properties of a material. The University has a long history of world-leading research in nonlinear optics, dating back to Kerr's discovery of the electro-optic and magneto-optic effects in the 19th centuary. More information on Kerr's experiments, some of which are exhibited in the Hunterian Museum can be found HERE.
Our current research is concentrated on the nonlinear optical properties of III-V semiconductor heterostructure waveguides. These have been used to demonstrate optical frequency conversion, all-optical switching, spatial, discrete and temporal solitons, mode-locking and ultrafast pulse measurement. Our collaborations extend worldwide and include CREOL (University of Central Florida), University of Toronto, Weizman Institute, Univ. du Quebec, THALES, University Rome Tre and St. Andrews University.
We have recently been developing a technique based on quantum well intermixing in superlattice waveguides to spatially modify the nonlinear optical coefficients. We have used this to demonstrate quasi-phase-matched second harmonic generation based on the modulation of the second-order coefficient and will be developing this theme towards integrated parametric amplifiers and sources. We also predict a substantial modulation in the third-order coefficient with applications for solitons and switching. For more information please view the presentations listed below.
Our research in optical frequency conversion and generation is supported by an new EPSRC project EP/E009972/1 Integrated self-pumped optical frequency conversion and generation in semiconductor waveguides in collaboration with the University of Toronto.
This project addresses an emerging demand for lowcost, compact and flexible optical sources in the near- and mid-infrared wavelength regions due particularly to increasing need for sensing applications, e.g. environmental, clinical analysis, life sciences, food monitoring, pharmaceutical, security and forensics. The principal advantage of the frequency conversion approach introduced here is that the wavelength to be generated is not fixed at the wafer growth stage, but is instead determined by lithography in the post-growth processing. As such it is feasible to conceive of several devices, each with modest tunability, monolithically integrated on a single semiconductor chip. This research builds on key technologies where we already have an extensive track record in semiconductor nonlinear optics, semiconductor ring lasers and III-V integration technologies. The minaturisation of infrared optical sources, in comparison to large and expensive desktop systems, will be enabled by fabricating the frequency conversion element within a high finesse semiconductor ring laser cavity.