Physics projects for Y3 and Y4 students

Project description

Simulating particle packing and ordering effects in Photonic Crystals

(supervisor: Chris Finlayson)

Nature of project: experimental, software

Available to students on full-time physics degree schemes or joint students.

Project description and methodology

All the laws of optics that you know start to break down when we make materials which are structured on the sub-micron size-scale of the wavelength of light, often called photonic crystals (PCs).[1] A subcategory of PCs involves the packing of mono-disperse particles into ordered arrays, by various means, with well-defined periodicity. New optical effects are then possible such as photonic bandgaps, structural colour[2], and optical switching.

In this project, the student will build, test, and analyse the packing of ellipsoidal particles in 2- and 3-D, in a scaled physical model. Photography and image processing methods will be employed to determine the ordering of ellipsoids over different length scales, whilst the confinement, shape, and scintillation of particles may be varied and optimised. An analogue system of interest for the packing of micro-spheres into photonic crystals is the so-called "polymer opals"(POs)[3], which is widely researched in the Dept.

A successful project will develop beyond the above in one/some of the following directions:
Development of existing image analysis and particle ordering/correlation determination tools.

In the event of Covid restrictions to lab access, suitable experimental microscopy data will be made available, as the project emphasis shifts to the image analysis element.

When considering where to take your project, please bear in mind the time available. It is preferable to do fewer things well than to try many and not get conclusive results on any of them. However, sometimes it is useful to have a couple of strands of investigation in parallel to work on in case delays occur.

Additional scope or challenge if taken as a Year-4 project: As a development, students may begin to explore how their experimental results correlate with theoretical dynamic simulation models of the forces between particles in POs[4], and how they form ordered arrays.

Please speak to Chris Finlayson if you consider doing this project.

Initial literature for students:

  1. http://en.wikipedia.org/wiki/Photonic_crystal
  2. P. Vukusic and J. R. Sambles, Nature, vol.424, p852 (2003)
  3. Q. Zhao et al., Nature Comms, vol.7, p11661 (2016)
  4. C. E. Finlayson et al., Optics Express, vol.19, p3144 (2011)

Novelty, degree of difficulty and amount of assistance required

The project is likely to feature a significant practical component, and is therefore best suited for highly motivated and industrious students.

Students will be given suitable training as required on any lab or workshop equipment. I believe that the project would be suitable for the average 3rd Year physics student.

Project milestones and deliverables (including timescale)

milestoneto be completed by
Initial familiarisation with experiments and equipmentChristmas
Generation of target models and simulationsend of February
Completion of experimental workmid-March
Analysis/results phaseEaster

Students taking this project will have to submit a full risk assessment form