Evolution of THz impulse imaging radar to 1550nm photoconductive switches

E. R. Brown; W.-D. Zhang; A. Feldman; T. Harvey; R. P. Mirin; S. Sung; W. S. Grundfest; Z. D. Taylor

doi:10.1117/12.2224919

26 May 2016 Evolution of THz impulse imaging radar to 1550nm photoconductive switches

E. R. Brown, W.-D. Zhang, A. Feldman, T. Harvey, R. P. Mirin, S. Sung, W. S. Grundfest, Z. D. Taylor

Proceedings Volume 9854, Image Sensing Technologies: Materials, Devices, Systems, and Applications III; 98540L (2016) https://doi.org/10.1117/12.2224919
Event: SPIE Commercial + Scientific Sensing and Imaging, 2016, Baltimore, MD, United States

Abstract

We present measurements of sub-bandgap photoconductivity and photoconductive switches using GaAs doped heavily with Er such that nanoparticles of ErAs are formed. In addition to strong resonant absorption centered around 1550 nm, the material provides strong sub-bandgap photoconductivity and >> μW average power levels when fabricated into an efficient (square spiral) THz antenna and driven by a 1550- nm ultrafast fiber laser. Photo-Hall measurements prove that the predominant photocarrier is the electron and the linearity of the 1550-nm photocurrent (with laser power) suggests that the photoconductivity is “extrinsic”, not other possible mechanisms, such as two-photon absorption. These results have immediate relevance to the use of GaAs:Er switches as the transmitter in 1550-nm-driven THz imaging systems such as the “impulse imager” that we have successfully used for biomedical imaging applications.

Citation Download Citation

E. R. Brown, W.-D. Zhang, A. Feldman, T. Harvey, R. P. Mirin, S. Sung, W. S. Grundfest, and Z. D. Taylor "Evolution of THz impulse imaging radar to 1550nm photoconductive switches", Proc. SPIE 9854, Image Sensing Technologies: Materials, Devices, Systems, and Applications III, 98540L (26 May 2016); https://doi.org/10.1117/12.2224919

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