Optically thin hybrid cavity for terahertz photo-conductive detectors

Journal Article · 23 January 2017 · Applied Physics Letters

DOI: https://doi.org/10.1063/1.4974482 · OSTI ID:1371477

Thompson, Robert J. ^[1]; Siday, T. ^[1]; Glass, S.  ^[1]; Luk, T. S. ^[2]; Reno, J. L. ^[2]; Brener, I. ^[2]; Mitrofanov, O. ^[3]

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1. Univ. College London, London (United Kingdom)
2. Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
3. Univ. College London, London (United Kingdom); Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

Here, 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.

• Research Organization: Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)
• Sponsoring Organization: USDOE National Nuclear Security Administration (NNSA)
• Grant/Contract Number: AC04-94AL85000
• OSTI ID: 1371477
• Report Number(s): SAND-2016-9000J; 655051
• Journal Information: Applied Physics Letters, Vol. 110, Issue 4; ISSN 0003-6951
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English