Dr. Thomas Siday Profile

Dr. Thomas Siday

PostDoc at Univ of Oxford

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Publications (6)

Proceedings Article | 5 March 2022 Presentation + Paper

Near-field nanoscopy of excitons and ultrafast interlayer dynamics in van der Waals crystals

Fabian Mooshammer, Markus Plankl, Paulo Faria, Sanghoon Chae, Thomas Siday, Martin Zizlsperger, Fabian Sandner, Felix Schiegl, Shuai Zhang, Yinming Shao, Aaron Sternbach, Daniel Rizzo, Simon Maier, Markus Huber, Martin Gmitra, Jaroslav Fabian, Jessica Boland, Xiaoyang Zhu, P. James Schuck, James Hone, Tyler Cocker, D. Basov, Rupert Huber

Proceedings Volume 12009, 120090D (2022) https://doi.org/10.1117/12.2603471

KEYWORDS: Excitons, Crystals, Ultrafast phenomena, Super resolution microscopy, Near field, Waveguide modes, Terahertz radiation, Dielectrics, Microscopy, Dispersion, Terahertz spectroscopy, Nanospectroscopy

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Proceedings Article | 9 September 2019 Presentation

Engineering perfect absorption in all-dielectric photoconductive metasurfaces (Conference Presentation)

Oleg Mitrofanov, Thomas Siday, Polina Vabishchevich, Lucy Hale, Thomas Harris, Ting Shan Luk, John Reno, Igal Brener

Proceedings Volume 11080, 110802Q (2019) https://doi.org/10.1117/12.2529419

KEYWORDS: Absorption, Resonators, Magnetism, Photonic devices, Optoelectronics, Switches, Sensors, Modulators, Gallium arsenide, Numerical simulations

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Proceedings Article | 6 September 2019 Presentation + Paper

Terahertz detectors based on all-dielectric photoconductive metasurfaces

Oleg Mitrofanov, Thomas Siday, Polina Vabishchevich, Lucy Hale, Charles Thomas Harris, Ting Shan Luk, John Reno, Igal Brener

Proceedings Volume 11124, 1112410 (2019) https://doi.org/10.1117/12.2529393

KEYWORDS: Terahertz radiation, Sensors, Absorption, Gallium arsenide, Photons, Resonators, Switching, Plasmonics, Millimeter wave sensors, Nanostructures

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Proceedings Article | 4 March 2019 Presentation

Improving efficiency of photoconductive terahertz detectors using all-dielectric optical metasurfaces (Conference Presentation)

Oleg Mitrofanov, Thomas Siday, Robert Thompson, Ting Shan Luk, Igal Brener, John Reno

Proceedings Volume 10922, 109220G (2019) https://doi.org/10.1117/12.2511142

KEYWORDS: Terahertz radiation, Sensors, Millimeter wave sensors, Near field optics, Plasmonics, Imaging spectroscopy, Switches, Nanostructures, Absorption, Channel projecting optics

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Detection of terahertz (THz) radiation with high sensitivity and efficiency remains a challenging problem for THz technology development. A photoconductive THz detector based on the Auston switch concept is among the most sensitive and widely-used room-temperature coherent THz detectors. Plasmonic nano-antennas and gratings, and ultrathin optical cavities recently were introduced in the structure of THz optoelectronic devices to improve their efficiencies. It allowed obtaining higher photocurrents and smaller capacitance, which lead to improvements in the response speed and efficiency of THz detectors. Plasmonic nanostructures however introduce Ohmic losses, which can substantially reduce the responsivity of THz detectors. Alternatively, efficiency of photoconductive THz detectors can be enhanced by using all-dielectric metasurfaces. A metasurface containing only dielectric, instead of plasmonic nanostructures, can be designed to trap the incident light in a selected spectral range and thus enhance optical absorption. We designed an optically-thin photoconductive channel as an all-dielectric metasurface, which exhibited enhanced optical absorption at laser excitation wavelength. The metasurface comprised an array of low-temperature grown GaAs nanobeams and a sub-surface distributed Bragg reflector. Integrated into a photoconductive (Auston) switch, the metasurface improved the efficiency and sensitivity of the THz detector. Specifically, the detector produced photocurrents over one order of magnitude higher compared to a similar detector with unstructured surface with only 0.5 mW of optical excitation, while exhibiting high dark resistance required for low-noise detection in THz time-domain spectroscopy and imaging. At that level of optical excitation the metasurface detector showed a high signal to noise ratio of 10^6. We will discuss mechanisms responsible for the efficiency improvement, as well as the application of THz detectors with all-dielectric metasurfaces for enabling more sensitive integrated THz near-field probes.

Proceedings Article | 23 February 2018 Presentation + Paper

An efficient terahertz detector based on an optical hybrid cavity

Thomas Siday, Robert Thompson, Samuel Glass, Ting-Shan Luk, John Reno, Igal Brener, Oleg Mitrofanov

Proceedings Volume 10531, 1053109 (2018) https://doi.org/10.1117/12.2290971

KEYWORDS: Nanoantennas, Terahertz radiation, Reflectivity, Gallium arsenide, Absorption, Sensors, Hybrid optics, Cavity resonators, Photonic nanostructures

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