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Proceedings Paper

A novel I-RTD based optically pulsed hybrid device for generating THz oscillations
Author(s): Weidong Zhang; Dwight Woolard; Elliott Brown; Boris Gelmont
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Paper Abstract

The double-barrier AlGaSb/InAs/AlGaSb heterostructure with staggered bandgap alignment can admit significant interband tunneling current in addition to the conduction band electron transport. The resulting positive hole-charge accumulation in the right valence-band (VB) well will electrostatically modify the spatial potential profile across the device structure, thereby effectively altering the conduction of conduction-band electron transport. A sequentially triggered optical discharging process can be used to annihilate, or substantially reduce, the trapped holes that are generated from the interband tunneling process. Hence, an artificially induced electro-optic interaction can be used to return the device to its initial state and to produce a two-cycle oscillation process - i.e., one with a interband-induced charging transient followed by a optically-induced discharging transient to the initial state. These charging-discharging cycles obtained from this hybrid type of interband resonant-tunneling-diode (I-RTD) device constitute steady-state oscillatory behavior at very high frequency and produce alternating-current (ac) power as long as very short (i.e., sub-picosecond) and intense far-infrared laser pulses are presented to the diode. Initial studies of non-optimized structures and designs predict impressive figures of merit for oscillation frequencies (e.g., ~ 300-600 GHz) and substantial output powers (e.g., ~ 10 mW) for very modest device areas (i.e., 100 μm2). This paper will present physics-based I-RTD diode simulation results to precisely describe transport dynamics and transient electric current for both charging (initiated by Zener tunneling) and discharging (artificially induced by photons flux) processes. A basic electro-optical design concept and modeling approach for the analysis and synthesis of non-linear hybrid I-RTD circuits will also be presented. The main objectives of this paper are: (1) to perform a detailed assessment of the ac output power and efficiency of an optically-triggered (OT) I-RTD hybrid oscillator in the frequency range approximately 300 to 600 GHz, and (2) to prescribe the general requirements for realizing a diode-laser pair upon a single solid-state platform in the future. Therefore, guidelines for a practical engineering implementation and performance estimates for an OT-I-RTD hybrid oscillator design will be presented.

Paper Details

Date Published: 5 November 2005
PDF: 12 pages
Proc. SPIE 5995, Chemical and Biological Standoff Detection III, 59950S (5 November 2005); doi: 10.1117/12.630570
Show Author Affiliations
Weidong Zhang, North Carolina State Univ. (United States)
Dwight Woolard, North Carolina State Univ. (United States)
U.S. Army Research Lab./Army Research Office (United States)
Elliott Brown, Univ. of California, Santa Barbara (United States)
Boris Gelmont, Univ. of Virginia (United States)

Published in SPIE Proceedings Vol. 5995:
Chemical and Biological Standoff Detection III
James O. Jensen; Jean-Marc Thériault, Editor(s)

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