Dr Calum Williams, PhD - University of Cambridge - Research Associate

Dr Calum Williams


University of Cambridge

Research Associate

Cambridge | United Kingdom

Additional Specialties: Optics and Photonics

ORCID logohttps://orcid.org/0000-0002-6432-6515

Dr Calum Williams, PhD - University of Cambridge - Research Associate

Dr Calum Williams



Today there exists a multitude of different optical imaging modalities used in the diagnosis and treatment of cancer. Calum is interested in applying concepts in nanophotonics to the illumination and detection sides of imaging, to unify different modalities (e.g. multispectral, polarimetric etc.) in a single system. This has great potential to change the way we image cancer using light, leading to better diagnostic accuracy and patient outcomes. The research is part of a multidisciplinary Cancer Research UK funded project with the researchers Dr. Sarah Bohndiek (Physics) and Prof. Timothy Wilkinson (Engineering). Calum also has research collaborations with Dr. Ventsislav Valev (University of Bath) and Dr. Hyun Jung Kim (NASA), involving the development of novel nanostructured optical devices for a range of applications.

Calum obtained a BSc (Hons) in Physics from Cardiff University (2011), an MPhil (Dist.) in Micro & Nanotechnology at the University of Cambridge (2012), and in 2013 joined the Photonic Systems Development Centre for Doctoral Training at the University of Cambridge. He completed his Ph.D. (Engineering) in 2017, with doctoral research in plasmonic nanostructures for enhanced optical devices. Calum is now a Postdoctoral Research Associate, funded by the Cancer Research UK Pioneer Award, and became a Junior Research Fellow at Wolfson College in 2018.

Calum is a Postdoctoral Researcher across the Departments of Engineering and Physics. He is member of the Institution of Engineering and Technology (IET) and the Optical Society (OSA).

Primary Affiliation: University of Cambridge - Cambridge , United Kingdom

Additional Specialties:

Research Interests:


Sep 2013 - Jun 2017
University of Cambridge
Doctor of Philosophy
Department of Engineering
Sep 2012 - Aug 2013
University of Cambridge
Photonic Systems Development, Master of Research (Dist)
Department of Engineering
Sep 2011 - Sep 2012
University of Cambridge
Micro & Nanotechnology, Master of Philosophy (Dist)
Department of Materials Science & Metallurgy
Sep 2008 - Sep 2011
Cardiff University
Physics, Bachelor of Science (Hons)
School of Physics and Astronomy


Jun 2013 - Sep 2013
Qioptiq Ltd
Technology research intern
Apr 2012 - Sep 2012
Nokia Research Center Cambridge UK
Student researcher
Research & Development
May 2017
University of Cambridge
Postdoctoral Research Associate
Department of Engineering




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13PubMed Central Citations

Grayscale-to-color: Single-step fabrication of bespoke multispectral filter arrays



Conventional cameras, such as in smartphones, capture wideband red, green and blue (RGB) spectral components, replicating human vision. Multispectral imaging (MSI) captures spatial and spectral information beyond our vision but typically requires bulky optical components and is expensive. Snapshot multispectral image sensors have been proposed as a key enabler for a plethora of MSI applications, from diagnostic medical imaging to remote sensing. To achieve low-cost and compact designs, spatially variant multispectral filter arrays (MSFAs) based on thin-film optical components are deposited atop image sensors. Conventional MSFAs achieve spectral filtering through either multi-layer stacks or pigment, requiring: complex mixtures of materials; additional lithographic steps for each additional wavelength; and large thicknesses to achieve high transmission efficiency. By contrast, we show here for the first time a single-step grayscale lithographic process that enables fabrication of bespoke MSFAs based on the Fabry-Perot resonances of spatially variant metal-insulator-metal (MIM) cavities, where the exposure dose controls insulator (cavity) thickness. We demonstrate customizable MSFAs scalable up to N-wavelength bands spanning the visible and near-infrared with high transmission efficiency (~75%) and narrow linewidths (~50 nm). Using this technique, we achieve multispectral imaging of several spectrally distinct target using our bespoke MIM-MSFAs fitted to a monochrome CMOS image sensor. Our unique framework provides an attractive alternative to conventional MSFA manufacture, by reducing both fabrication complexity and cost of these intricate optical devices, while increasing customizability.

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January 2019

Nanostructured plasmonic metapixels

Scientific Reports 7, 7745 (2017)

Scientific Reports

State-of-the-art pixels for high-resolution microdisplays utilize reflective surfaces on top of electrical backplanes. Each pixel is a single fixed color and will usually only modulate the amplitude of light. With the rise of nanophotonics, a pixel’s relatively large surface area (~10 μm2), is in effect underutilized. Considering the unique optical phenomena associated with plasmonic nanostructures, the scope for use in reflective pixel technology for increased functionality is vast. Yet in general, low reflectance due to plasmonic losses, and sub-optimal design schemes, have limited the real-world application. Here we demonstrate the plasmonic metapixel; which permits high reflection capability whilst providing vivid, polarization switchable, wide color gamut filtering. Ultra-thin nanostructured metal-insulator-metal geometries result in the excitation of hybridized absorption modes across the visible spectrum. These modes include surface plasmons and quasi-guided modes, and by tailoring the absorption modes to exist either side of target wavelengths, we achieve pixels with polarization dependent multicolor reflection on mirror-like surfaces. Because the target wavelength is not part of a plasmonic process, subtractive color filtering and mirror-like reflection occurs. We demonstrate wide color-range pixels, RGB pixel designs, and in-plane Gaussian profile pixels that have the potential to enable new functionality beyond that of a conventional ‘square’ pixel.

View Article
August 2017
71 Reads

Fabrication of nanostructured transmissive optical devices on ITO-glass with UV1116 photoresist using high-energy electron beam lithography.

Nanotechnology 2016 Dec 4;27(48):485301. Epub 2016 Nov 4.

Electrical Engineering Division, Department of Engineering, University of Cambridge, 9 JJ Thomson Avenue, Cambridge CB3 0FA, UK.

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http://dx.doi.org/10.1088/0957-4484/27/48/485301DOI Listing
December 2016
4 Reads
1 Citation
3.821 Impact Factor

Plasmonic nanoparticle scattering for color holograms.

Proc Natl Acad Sci U S A 2014 Sep 13;111(35):12679-83. Epub 2014 Aug 13.

Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge CB3 0FA, United Kingdom; and.

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http://dx.doi.org/10.1073/pnas.1405262111DOI Listing
September 2014
4 Reads
11 Citations
9.810 Impact Factor