School of Physics & Astronomy

Find a PhD Project Here

Opportunities for fully funded PhD or EngDoc research projects are available in all fields of research within the School. You may search for current projects on this page. APPLY HERE for a PhD Place.

 PhD in Photonics
 PhD in Condensed Matter
 PhD in Astrophysics

Search current PhD opportunities in the School of Physics & Astronomy:-




Photonics

Slow and structured light in nanophotonics
Schulz, Dr Sebastian - sas35@st-andrews.ac.uk

Slow light waveguides have the potential to strongly enhance light matter interactions, leading to efficient non-linear optical processes, optical switches and optical modulators amongst other applications [1]. On a photonic chip slow light is typically realized through Photonic Crystal waveguides or coupled optical resonator waveguides [2], with the speed of light typically between 1/ 10 and 1/100 of the free space value. However, all these realizations suffer from optical scattering from fabrication defects [2-4], leading to optical losses and light localization, limiting the current device performance and rendering physical concepts such as the group velocity meaningless. Yet at the same time optical information can travel through completely opaque materials, implying that the current limit – not using photonic devices in the strong scattering regime - is self-imposed.

In this project you will investigate new slow light waveguide designs, leading to further reductions in the group velocity, while simultaneously reducing the optical losses and scattering. You will address fundamental questions about the behaviour of light and information in scattering media, for example: “At what velocity does information travel through a disordered system and how is this dependent on the disorder level in the system?”. You will investigate the effect of slow light on topics at the forefront of integrated photonics research, for example the use of complex polarization states in integrated optics and how this is affected by the disorder present in real world systems.

You will learn nanofabrication, optical simulation and characterisation techniques and gain a deep understanding of complex physical systems. You will interact with collaborators both in the UK and abroad, giving you the opportunity to visit their laboratories and build your own professional network.

The project will be supervised by Dr. Sebastian Schulz, who will join the department in March 2018. For more details on this topic and for any question regarding the project, please contact Dr. Sebastian Schulz (Sebastian.Schulz@cit.ie).

[1] T. F. Krauss “Why do we need slow light” Nature Photonics 2, p 448-450 (2008). https://www.nature.com/articles/nphoton.2008.139
[2] S. A. Schulz, L. O’Faolain, D. M. Beggs, T. P. White, A. Melloni and T. F. Krauss “Dispersion engineered slow light in photonic crystals: a comparison” Journal of Optics 12, 104004 (2010). http://iopscience.iop.org/article/10.1088/2040-8978/12/10/104004/meta
[3] S. Mazoyer, J. P. Hugonin and P. Lalanne “Disorder-induced Multiple scattering in Photonic-Crystal Waveguides” Physical Review Letters 103, 063903 (2009). https://journals.aps.org/prl/abstract/10.1103/PhysRevLett.103.063903
[4] L. O’Faolain, S. A. Schulz, D. M. Beggs, T. P. White, M. Spasenovic, L. Kuipers, F. Morichetti, A. Melloni, S. Mazoyer, J. P. Hugonin, P. Lalanne and T. F. Krauss “Loss engineered slow light waveguides” Optics Express 18, pp.27627-27638 (2010). https://doi.org/10.1364/OE.18.027627
Non-reciprocal optics
Schulz, Dr Sebastian - sas35@st-andrews.ac.uk

In contrast to traditional, reciprocal optical systems, non-reciprocal systems allow the realization of interesting physical effects, for example optical isolation or the breaking of seemingly fundamental physical limits, such as the link between a system’s delay and its bandwidth [1]. Typically, non-reciprocal optical elements are realized using magneto-optic materials, for example in a Faraday Rotator. However, these materials are not suitable for integration in nanophotonic devices and thus new methods of achieving non-reciprocity need to be explored, for example nonlinear optical effects or time-variant modulations [2-4].

This project addresses the realization of on-chip non-reciprocal optical elements, new applications enabled by these elements and the exciting new physics achieved by combining non-reciprocal elements with components such as absorbers, emitters or resonators [1].

You are expected to have an interest in studying fundamental concepts in physics as well as mastering hands on nanofabrication and laboratory techniques. The project includes collaborations with groups across Europe and North America, offering you opportunities to visit the laboratories of collaborators and to build your own professional network.

The project will be supervised by Dr. Sebastian Schulz, who will join the department in March 2018. For more details on this topic and for any question regarding the project, please contact Dr. Sebastian Schulz (Sebastian.Schulz@cit.ie).

[1] H. Tsakmakidis, L. Shen, S. A. Schulz, X. Zheng, J. Upham, X. Deng, H. Altug, A. F. Vakakis and R. W. Boyd “Breaking Lorentz reciprocity to overcome the time-bandwidth limit in physics and engineering” Science 356, pp1260-1264 (2017). http://science.sciencemag.org/content/356/6344/1260

[2] E. A. Kittlaus, N. T. Otterstrom and P. Rakich “On-chip inter-modal Brillouin Scattering” Nature Communications 8, p.15819 (2017). https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5504300/

[3] L. Feng, M. Ayache, J. Huang, Y.-L. Xu, M.-H. Lu, Y.-F. Chen, Y. Fainman and A. Scherer “Nonreciprocal Light Propagation in Silicon Photonic Circuit” Science 333, p. 729 (2011). http://science.sciencemag.org/content/333/6043/729

[4] D. L. Sounas and A. Alu “Non-reciprocal photonics based on time modulation” Nature Photonics 11, p 774 (2017). https://www.nature.com/articles/s41566-017-0051-x