Center for Integrated Technologies

Albuquerque, MN, United States

Center for Integrated Technologies

Albuquerque, MN, United States
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Thompson R.J.,University College London | Siday T.,University College London | Glass S.,University College London | Luk T.S.,Center for Integrated Technologies | And 7 more authors.
Applied Physics Letters | Year: 2017

The efficiency of photoconductive (PC) devices, including terahertz detectors, is constrained by the bulk optical constants of PC materials. Here, we show that optical absorption in a PC layer can be modified substantially within a hybrid cavity containing nanoantennas and a Distributed Bragg Reflector. We find that a hybrid cavity, consisting of a GaAs PC layer of just 50 nm, can be used to absorb >75% of incident photons by trapping the light within the cavity. We provide an intuitive model, which describes the dependence of the optimum operation wavelength on the cavity thickness. We also find that the nanoantenna size is a critical parameter, small variations of which lead to both wavelength shifting and reduced absorption in the cavity, suggesting that impedance matching is key for achieving efficient absorption in the optically thin hybrid cavities. © 2017 Author(s).


Khromova I.,University College London | Khromova I.,Saint Petersburg State University of Information Technologies, Mechanics and Optics | Mitrofanov O.,University College London | Navarro-Cia M.,Imperial College London | And 5 more authors.
2015 9th International Congress on Advanced Electromagnetic Materials in Microwaves and Optics, METAMATERIALS 2015 | Year: 2015

Microsized carbon fibres exhibit strong resonant absorption at terahertz frequencies. Using near-field terahertz time-domain spectroscopy, we probe their conductivity by analysing the degree of field enhancement produced by plasmonic resonances. We demonstrate, theoretically and experimentally, the potential usability of carbon microfibres as terahertz absorbers with engineerable response. © 2015 IEEE.


Mitrofanov O.,University College London | Khromova I.,University College London | Khromova I.,Saint Petersburg State University of Information Technologies, Mechanics and Optics | Dominec F.,Sandia National Laboratories | And 9 more authors.
Optical Sensors, Sensors 2015 | Year: 2015

We demonstrate THz near-field spectroscopy of resonances in sub-wavelength size dielectric and conductive structures using the effect of enhanced transmission through a sub-wavelength aperture in the presence on a resonator. © 2015 OSA.


Mitrofanov O.,University College London | Mitrofanov O.,Center for Integrated Technologies | Thompson R.,University College London | Brener I.,Center for Integrated Technologies | And 7 more authors.
CLEO: Science and Innovations, CLEO_SI 2013 | Year: 2013

We use THz near-field microscopy with broadband THz pulses to image graphene nano-ribbons and to probe surface plasmon excitation and uniformity of graphene response. 3.3nm and 7nm thick graphene layers induce (~10%) absorption from 0.5-2.5THz. © OSA 2013.


Macfaden A.J.,University College London | Reno J.L.,Center for Integrated Technologies | Reno J.L.,Sandia National Laboratories | Brener I.,Center for Integrated Technologies | And 3 more authors.
Optics InfoBase Conference Papers | Year: 2014

We demonstrate that THz pulses transmitted through small apertures (~λ/100) exhibit strong evanescent components within 1μm of the aperture. Using this effect, we developed subwavelength aperture THz near-field probes that provide 3μm resolution. © 2014 OSA.


Mitrofanov O.,University College London | Mitrofanov O.,Center for Integrated Technologies | Brener I.,Center for Integrated Technologies | Brener I.,Sandia National Laboratories | And 4 more authors.
ACS Photonics | Year: 2015

Nanoscale structuring of optical materials leads to modification of their properties and can be used for improving efficiencies of photonic devices and for enabling new functionalities. In ultrafast optoelectronic switches for generation and detection of terahertz (THz) radiation, incorporation of nanostructures allows us to overcome inherent limitations of photoconductive materials. We propose and demonstrate a nanostructured photoconductive THz detector for sampling highly localized THz fields, down to the level of λ/150. The nanostructure that consists of an array of optical nanoantennas and a distributed Bragg reflector forms a hybrid cavity, which traps optical gate pulses within the photoconductive layer. The effect of photon trapping is observed as enhanced absorption at a designed wavelength. This optically thin photoconductive THz detector allows us to detect highly confined evanescent THz fields coupled through a deeply subwavelength aperture as small as 2 μm (λ/150 at 1 THz). By monolithically integrating the THz detector with apertures ranging from 2 to 5 μm we realize higher spatial resolution and higher sensitivity in aperture-type THz near-field microscopy and THz time-domain spectroscopy. © 2015 American Chemical Society.

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