Conference Agenda

A variety of applications requires light and infrared radiation to be shaped and controlled actively. In our laboratory we are working on shaping light using silicon photonics on a chip and in free space using metasurfaces. Key to these applications are materials that can be tuned or switched optically, electrically or thermally. In this presentation I will give an overview of cutting edge developments in shaping of light using phase change materials. I will also address efforts at modelling these effects using new techniques from the toolbox of deep learning neural networks.

We show that, by exploiting the optical memory effect, it is possible to track a moving object through a strongly scattering layer, despite its image being obscured to us.

Here we propose to exploit the natural instability of thin solid films, i.e. solid state dewetting, to form regular patterns of monocrystalline atomically smooth Si, Si1-xGex and Ge nanostructures that cannot be realized with conventional methods. Additionally, the solid-state dewetting dynamics is guided by prepatterning the sample by a combination of electron-beam lithography and reactive-ion etching, obtaining precise control over number, size, shape, and relative position of the final structures. Methods and structures will be optimized towards their exploitation mainly in photonic devices application (e.g. anti-reflection coatings, colour-filters, random lasers, quantum emitters and photonic sensors).

Spin-orbit coupling in nanoscale optical fields induces the formation of a spin momentum component transverse to the orbital momentum. Herein, we firstly explore the manipulation of dynamics by the spin-orbit effect on gold monomers, observing how the self-induced spin from localized resonance results in trajectory shifts controlled by the incident polarization. Secondly, we discuss the spin-orbit behavior in systems of gold dimers that due to field hybridization effects within the gap exhibit changes in the nontrivial spin momentum that lead to the formation of a vortex and anti-vortex spin angular momentum (SAM) pair on the opposite surfaces of the nanoparticles. The results could offer advantages for biological and aerospace fields, leading to the development of new systems and applications in the field of spin-optics.

Photonic band gap crystals are being pursued for their ability to control emission and vacuum fluctuations radically. Here, we examine the spontaneous emission of lead sulfide quantum dot nanocrystals within 3D photonic band gap crystals. These crystals, formed by etching deep pores in a silicon bar from two directions, possess a diamond-like inverse-woodpile structure, with quantum dots infiltrated into the pores using a toluene suspension. At frequencies just above the band gap, we observe >18x more intensity from quantum dots inside the crystal than the same number of dots outside, indicative of strongly enhanced emission. Time-correlated single photon counting shows fast non-exponential decay, reflecting the varied local densities of states of different quantum dots within the nanopores. We employ a log-normal model to interpret properties of the time-resolved decay at different emission frequencies and observe that the most frequently occurring decay rate is up to a factor 10x greater in the photonic crystal than outside. Current efforts focus on enhancing signal-to-background and signal-to-noise ratio, essential for probing inhibited decay within the band gap, and further studies on 3D band gap cavity superlattices and quasicrystals.