New design for increased terahertz power from LTG GaAs photomixers

D. J. Yeh; Elliott R. Brown

doi:10.1117/12.422171

18 December 2000 New design for increased terahertz power from LTG GaAs photomixers

D. J. Yeh, Elliott R. Brown

Proceedings Volume 4111, Terahertz and Gigahertz Electronics and Photonics II; (2000) https://doi.org/10.1117/12.422171
Event: International Symposium on Optical Science and Technology, 2000, San Diego, CA, United States

Abstract

Photoconductive mixing in ultrafast photoconductors (LTG- GaAs) represents an optoelectronic means of generating coherent radiation at THz frequencies form optical pump laser. TO dat the power from such photomixers has been limited to microwatt levels by thermal burn-out. In this paper, we analyze a new design in which the LTG-GaAs is fabricated both in a resonant planar dipole and in a vertical optical cavity. This is accomplished with an electrically-floating metal layer lying below the thin LTG- GaAs layer by approximately 0.5 micron. Optical analysis shows that the metal layer can increase the external quantum efficiency of the photomixer approximately 3 times through creation of a vertical optical cavity int eh LTG-GaAs layer. Heat-transfer analysis shows that the metal layer reduces the photomixer thermal resistance approximately 2.5 times, allowing for an increase in the optical pump power by roughly the same factor. Finally, full-wave electromagnetic analysis shows that the metal layer has a small impact on the radiation pattern of the planar dipole above it, presumably because the layer is much smaller laterally than a wavelength and is electrically floating. In total, these beneficial effects are predicted to increase the output THz power by approximately a factor of ten compared to any result reported to date.

Citation Download Citation

D. J. Yeh and Elliott R. Brown "New design for increased terahertz power from LTG GaAs photomixers", Proc. SPIE 4111, Terahertz and Gigahertz Electronics and Photonics II, (18 December 2000); https://doi.org/10.1117/12.422171

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