Distributed photomixers

Although the terahertz domain has been explored scientifically, components, especially sources, are needed to enable further exploration of the frequency range. A photomixer generates coherent THz radiation through optical heterodyne down-conversion. A terahertz-frequency beat signal on an optical carrier illuminates an ultrafast photoconductor, modulating the conductance. The time-varying conductance together with a constant voltage bias generates time-varying current at the beat frequency. Low-temperature-grown gallium arsenide (LTG-GaAs) is the photoconductive material of choice, because its short carrier lifetime allows the conductance to be efficiently modulated at THz frequencies. The distributed photomixer described in this thesis is a new style of LTG-GaAs photomixer which uses an optical waveguide to couple the beat signal to an active area whichis large relative to the terahertz wavelength. This large, traveling-wave mode active area distributes the heat load from absorbed optical power and ohmic heating from photocurrent and avoids the RC rolloff associated with a lumped-element photomixer's intrinsic capacitance and the load resistance. The distributed photomixer structure consists of coplanar strips (CPS) fabricated on top of a dielectric strip-loaded waveguide that guides the optical beat.

Department dc:contributor.department

Massachusetts Institute of Technology. Dept. of Electrical Engineering and Computer Science.

Grantor dc:publisher

Massachusetts Institute of Technology

Year dc:date.issued

2002

Author dc:creator

• Duerr, Erik Kurt, 1973-

Advisor dc:contributor.advisor

• Qing Hu.

• Electrical Engineering and Computer Science.

Statement dc:rights

• M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission.

Licence dc:rights.uri

• http://dspace.mit.edu/handle/1721.1/7582

Language dc:language.iso

eng

Handle dc:identifier.uri

http://hdl.handle.net/1721.1/16895

OAI identifier oai:identifier

oai:dspace.mit.edu:1721.1/16895