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1.55 micron InGaAs THz Synchronized Photoconductive Switch Array

Williams, Kimani Kwesi
Degree Grantor:
University of California, Santa Barbara.Electrical & Computer Engineering
Degree Supervisor:
Blumenthal Daniel J
Place of Publication:
[Santa Barbara, Calif.]
University of California, Santa Barbara
Creation Date:
Issued Date:
Electrical engineering, Packaging, and Materials Science
Square spiral antenna
Semimetal nanoparticles
1.55 micron Photoconductive Array
Photoconductive Switch

1.55 micron InGaAs THz Synchronized Photoconductive Switch Array


Kimani K. Williams

Metal-particle-in-semiconductor nanocomposites are of continuing

interest in materials science to produce electronic, photonic, and

thermoelectric devices, as well as chemical and biological nanosensors. These materials have successfully been employed for THz photoconductive devices operating at 800 nm. To date, producing devices operating at the desirable pump wavelength of 1.55 micron at which both mode-locked and single-frequency lasers needed for THz generation are readily available, remains challenging. Excessive dark current and prohibitively low breakdown voltage have been the primary impediments.

Recent research has shown that ErAs:In0.53Ga0.47As designed for

subpicosecond photoconductivity exhibits an exponential increase in

resistivity when cooled to temperatures below 250 K. This increased

resistivity gives promise to producing THz sources since higher bias

voltages can be used, thus increasing the optical to THz conversion


One of the major limitations of THz photoconductive sources is that it

is challenging to harness sizeable power. Typical power levels generated by THz sources at 1.55 micron are generally in the low microwatts region. This dissertation demonstrates a 1.55 micron THz synchronized linear array that maximizes power and has attained an impressive maximum peak power of 123 microwatts. In addition, THz beam steering at 1.55 micron by phase control in the time domain is a young field. Beam steering is demonstrated with this phased array up to 14.6 degrees using optical delay line units. The possibility of beam steering will prove beneficial in various applications, particularly in standoff imaging.

UCSB electronic theses and dissertations
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