As reported soon in Physical Review Letters, we have constructed a spectral lens, that is, a nanostructure that can either expand (“magnify”) or compress (“demagnify”) the spectrum of light. This lens could find application in spectroscopy (to improve the resolution of spectrometers) or in optical data transfer (to reduce the bandwidth of a signal).
Four members of the group have been selected to attend the "JSPS International Schooling on Si Photoincs 2011" to be held in Kyoto, Japan between November 16-19, 2011. They have each also been awarded a full scholarship to cover all costs of their participation.
Eight of our research team participate in "Group IV Photonics 2011" held in London. Andrea and Isabella both presented talks which were greatly received (Andrea even mangaged to squeeze in 3 "final" slides!!). Two of our delegates, Isabella and Abdul, were also selected for the MPAGs student scholarship
Sebastian wins "Best Student Paper" at the Advanced Photonics Congress, held by the Optical Society of America (OSA) in Toronto, Canada. The US$ 1000 award recognised Sebastian's paper "Understanding losses in photonic crystal waveguides" both for scientific merit and excellence of delivery.
Paolo Cardile is awarded the Young Scientist Award in recognition of the outstanding paper he contributed to the Symposium I Transport and Photonics in Si-based Nanomaterials and Nanodevices at the 2011 E-MRS Spring Meeting IUMRS & E-MRS/MRS Bilateral Energy Conferences.
Illustration of a slow-light optical buffer. At the entrance, the header is switched out and travels (fast); meanwhile, the "payload" is stored in the buffer.
The focus of the group is on functional nanostructured photonic devices. We are the leading planar photonic crystals research group in the Europe and amongst the leaders worldwide. We have been active for over a decade and have made some pioneering demonstrations, starting from; the first demonstration of a two dimensional photonic bandgap in semiconductor waveguides (Nature, 1996) and the superprism effect (Journal of Lightwave Technology, 2003) to the lowest loss photonic crystal waveguides in Europe (Optics Express, 2006) and slow light enhanced nonlinear effects (Nature Photonics, 2009). The key driving force is to use nanostructures for enhancing light-matter interaction, be it for low power nonlinear optical interactions, miniaturised electro-optical devices, efficient nanoscale light emitters or advanced biosensors. Slow light is a major theme and a particularly exciting area of research as it is the key enabling phenomenon behind many of the applications, yet it is also a fascinating research topic in its own right. For example, we have recently made major advances in understanding the nature of propagation losses and how they can be mitigated in order to achieve slow light without incurring high losses. Slow light is based on dispersion engineered photonic crystal waveguides, and more recently, similar dispersion engineering concepts have also been applied to cavities and yielded, for example, the demonstration of blue light generation via third harmonic processes, using only sub-mW pump powers (IEEE Journal of Selected Topics in Quantum Electronic, Optics Express, 2010).
Our Biophotonics research area aims to use the sophisticated technology developed for the fabrication of photonic crystals and lasers in a different context, namely micro-manipulation and sensitive detection for biomedical applications. Integration of optoelectronic and microfluidic concepts results in novel lab-on-a-chip concepts. Miniaturisation is the key, as it allows for many devices to be integrated in a multimodal platform or for devices to be placed into tiny spaces such as surgical instruments.
Very recently, we have started to engage in energy-related research with the aim of applying our photonic crystal expertise to the problem of light trapping in thin film solar cells. Multiperiodic and quasicrystalline structures are the most promising candidates for increasing the absoption efficiencies yet allowing to reduce the material thickness and hence the cost.
Photonic Crystals are wavelength scale, periodic, dielectric microstructures. Their periodic patterning creates photonic band gaps which forbid the propagation of light through the structure. The periodicity couples forward- and backward-travelling waves inside the Photonic Crystal (PhC), causing a net cancellation of the optical field. PhCs therefore insulate photons in a manner similar to which electrons are insulated in a semiconductor crystal.
The group have worked on a wide variety of planar PhC elements, building discrete components for integrated optical circuitry. Even more important however is the ability to control the speed of propogation of light in Photonic Crystal waveguides. We aim to take advantage of the strong temporal dispersion of 2D PhC waveguides for pulse delay lines and dispersion compensation. The first 2D planar PhC superprism demonstrated in 2002 takes a step towards producing much more compact spatially dispersive elements, with improved resolution. Slow Light in Photonic Crystal Waveguides
Miniaturised optical switch exploiting slow light effects in order to reduce the switching length 40-fold to 5 µm for a given refractive index shift of 4x10-3
Microfluidics is becoming an increasingly important part of MEMS research with areas such as ‘Lab-on-a-chip’ and ‘microTAS’ growing in size and scope. We aim to combine our abilities in microfabrication with expertise in micromanipulation from the Optical Trapping group at St Andrews to allow us to create novel devices and perform research of an international standard in these areas. A current project is the integration of microfabricated monolithic lasers with micro channels to allow on-chip optical tweezing. This would allow the mass fabrication of devices that could use optical trapping for pumping, sorting or detection of biological specimens in a ‘Lab-on-a-chip’ enviroment.
One of the projects is the simulation, fabrication and testing of microgears that can be controlled via form birefringence. These gears could be used to power a micromachine such as a micropump.