Carl Brown

Carl Brown

Head of the NTU Doctoral School

NTU Doctoral School

Staff Group(s)
Physics and Mathematics

Role

Professor Carl Brown is Module Leader for:

  • Condensed Matter Physics (PHYS3213)
  • Research Methods in Physics / Astronomy / Instrumentation (PHYS2161)
  • Work Experience (PHYS22621) and Ballistics and Firearms (PHYS32711).

His teaching contributions are made to Experimental Techniques (PHYS3053) and Level Three Projects (PHYS3001).

Research areas

Professor Brown is a member of the Optics and Displays research group.

Current research is being carried out in the following areas of Materials Physics:

  • Bistable Nematic Liquid Crystal Displays - Bistable liquid crystal modes have the ability to retain an image in the power off state and therefore have very high potential for use in low power displays for mobile phones, games and camcorders. Bistable liquid crystal device modes can be produced by the alignment of nematic liquid crystals across grooved surfaces - one such nematic device, the ZBD Display, was co-invented at QinetiQ by Professor Carl Brown. This device has been shown to switch via an induced polarisation called the flexoelectric polarisation. This polarisation effect is being investigated, both theoretically and experimentally, using the Freedericksz effect in the presence of mobile ionic contamination, and using a newly developed transient capacitance technique.
  • Multistable Photonic Devices - The development of multi-level, multi-stable switchable phase structures is of significant importance for photonic switching since bi / multistability in optical telecommunications switches will enable (i) enhanced network security after a power outage, since the device would continue to operate and be optically transparent, and (ii) redundancy management, where semi permanent re-routing can easily be implemented. In this project, they are building on recent work where they have demonstrated the possibility of not only bistability, but multistability, by micro-structuring the sidewall in a planar aligned liquid crystal layer in order to control alignment. The use of the sidewall avoids the need for index matching with surface structures and allows for more functionality in the substrate surface, for instance so that it can be used as an active waveguide cladding.
  • Optical devices based on electrowetting - These devices are promising for low power flexible displays and for optically transparent and polarisation insensitive switching in optical interconnects. In electrowetting, a liquid forms one of the conducting contacts in a substrate-insulator-liquid capacitive structure. Applying a voltage modifies the balance of surface free energies at the solid-liquid interface, causes spreading and so results in a modification of the radius of curvature in the meniscus at the liquid-air interface. In devices this principle is applied to modify the meniscus at an oil-water (rather than liquid-air) interface. Part of the current research involves the fabrication of suitable surface patterns to demonstrate polarisation independent phase grating structures using interference to produce a diffractive optical effect.

Opportunities arise to carry out postgraduate research towards an MPhil / PhD in the areas identified above. Further information may be obtained from the NTU Graduate School.

External activity

Professor Carl Brown is a Member of the Academic Board.

Sponsors and collaborators

Current and recent research is being carried out in collaboration with, or funded by:

  • Engineering and Physical Sciences Research Council
  • Scottish Enterprise
  • Kodak European Research Ltd
  • QinetiQ (Malvern)
  • Merck NB-C (Chilwell, Southampton).

Research funding has included:

  • Exploiting the solid-liquid interface, EPSRC EP/E063489/1 (2007 to 2012), £644,000
  • Sidewall control of multistate switchable photonic devices, EPSRC EP/F014988/1 (2007 to 2010), £255,000
  • Spatial light modulator based on electrowetting technology, Kodak (2005 to 2009), £79,000
  • A novel bistable liquid crystal device for portable display device applications, Scottish Enterprise (2005 to 2007) £70,000
  • Flexoelectricity and ordering in nematic liquid crystals, EPSRC GR/S90621/01 (2004 to 2007), £157,000
  • Bistable nematic liquid crystal displays, EPSRC GR/R17423/01 (2001 to 2005), £161,000
  • Development and numerical modelling of optically addressed spatial light modulator technology, QinetiQ, £214,000.

Publications

Selected publications

  • Voltage-induced spreading and superspreading of liquids. McHale G, Brown CV and Sampara N, Nature Communications, 2013, 4, 1605
  • Diffraction grating with suppressed zero order fabricated using dielectric forces. Brown CV, Wells GG, Sampara N, Kriezis EE, Fyson J, Optics Letters, 2011, 36 (22), 4404-4406
  • Dielectrowetting driven spreading of droplets.  Brown CV, McHale G, Newton MI, Wells GG, Sampara N, Physical Review Letters, 2011, 107 (18)
  • Voltage-programmable liquid optical interface. Brown CV, Wells GG, Newton MI and McHale G, Nature Photonics, 2009, 3, 420
  • Rotatable liquid crystal waveplate. Brown CV and Wells GG, Journal of Materials Science: Materials in Electronics, 2009, 20 (1), 175-180
  • Interferometric method for determining the sum of the flexoelectric coefficients (e(1)+e(3)) in an ionic nematic material. Brown CV, Trabi CL, Smith AAT and Mottram NJ, Applied Physics Letters, 2008, 92 (22)
  • Liquid crystal diffractive optical elements. Brown CV and Kriezis EE,  Handbook of Organic Electronics and Photonics Volume Two, (ed) Nalwa HS, American Scientific Publishers, 2008, 8, 235-299
  • Multistable liquid crystal waveplate, Brown CV and Wells GG, Applied Physics Letters, 2007, 91, 223506
  • Theoretical analysis of the magnetic freedericksz transition in the presence of flexoelectricity and ionic contamination, Brown CV, Smith AT and Mottram NJ, Physical Review E. 2007, 75, 041704

See all of Carl Brown's publications...

Press expertise

  • 3D TV technology
  • Ebook reader displays technology
  • Electronic paper technology
  • LCD TV technology
  • LED TV technology