Dr. William S. Kolthammer Profile

Dr. William S. Kolthammer

Postdoctoral Fellow at Imperial College London

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Publications (3)

Proceedings Article | 4 March 2019 Presentation

Modular linear optical circuits for quantum information processing (Conference Presentation)

James Gates, Paolo Mennea, William Clements, Devin Smith, Rex H. Bannerman, Jelmer Renema, William Kolthammer, Ian Walmsley, Peter G. Smith

Proceedings Volume 10933, 109330A (2019) https://doi.org/10.1117/12.2510301

KEYWORDS: Quantum information processing, Optical circuits, Integrated optics, Phase shifts, Waveguides, Ultraviolet radiation, Photonics, Silica, Interferometers, Thermal optics

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For over a decade the field of quantum photonics has increasingly looked towards optical integrated platforms to perform more complex and sophisticated experiments. Silica integrated optics is an ideal material for this area, offering low propagation and fibre-coupling losses. To date many of the key on-chip experiments have been carried out in this platform, using bespoke monolithic devices. In this work we propose an alternative approach, implementing a linear network constructed from a number of identical reconfigurable modules. The modules are measured separately to produce an accurate model of the overall network. The cellular nature also allows the replacement of modules that are faulty or substandard. Each module comprises of an array of 10 Mach-Zhender interferometers. Forty thermo-optic phase shifters on each chip allows the control of both the amplitude and phase of the optical field within the devices. By cascading the modules any arbitrary NxN unitary network can be realised. The optical waveguides within the modules are fabricated by direct UV writing, where a scanning focused UV laser beam increases the local refractive index within a photosensitive germanosilicate glass layer. The resulting channel waveguides are engineered to have dimensions that are mode matched to standard optical fibre producing excellent coupling efficiency. Bragg gratings can also be simultaneously produced within the waveguides which greatly assists in the precise characterisation of the phase shifters, coupling ratios and optical losses within the modules. We will present our recent work in this area, demonstrating devices operating at telecom wavelengths for quantum information processing. We present a modular reconfigurable system for on-chip quantum optics experiments with excellent fibre compatibility and low propagation losses, implemented using direct-UV-written silica-on-silicon. The performance of fabricated devices in various configurations is reported.

Proceedings Article | 22 February 2018 Presentation + Paper

Fiber coupled acousto-optic modulators for near UV and blue wavelength applications

M. Swain, M. Farries , M. Christie , T. Reid, J. Ward, C. Ballance, W. Kolthammer, P. Gow, D. O'Brien

Proceedings Volume 10547, 105470J (2018) https://doi.org/10.1117/12.2287718

KEYWORDS: Bragg cells, Near ultraviolet, Acousto-optics, Fiber couplers, Quantum computing, Diffraction, Switching, Ultraviolet radiation, Ions

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Proceedings Article | 6 March 2013 Paper

Towards scalable photonics via quantum storage

J. Nunn, N. Langford, W. Kolthammer, T. F. Champion, M. Sprague, P. Michelberger, X.-M. Jin, D. England, I. Walmsley

Proceedings Volume 8636, 863612 (2013) https://doi.org/10.1117/12.2012487

KEYWORDS: Photons, Quantum memory, Single photon, Photonics, Quantum optics, Quantum information processing, Neodymium, Multiplexing, Scattering, Clocks

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