Dr. Weidong Zhang Profile

Dr. Weidong Zhang

Research Associate

SPIE Involvement:

Author

Publications (6)

Proceedings Article | 7 March 2012 Paper

Concentration methods for high-resolution THz spectroscopy of nucleic-acid biomolecules and crystals

E. Brown, W. Zhang, E. Mendoza, Y. Kuznetsova, S. R. Brueck, M. Rahman, M. Norton

Proceedings Volume 8221, 82210S (2012) https://doi.org/10.1117/12.912219

KEYWORDS: Terahertz radiation, Crystals, Spectroscopy, Waveguides, Molecules, Absorption, Silica, Metals, Photoresist materials, Free space

Read Abstract +

Proceedings Article | 28 February 2012 Paper

THz lasing in InAs/GaSb broken-gap heterostructure devices and quantum-dot pillar arrays

Dwight Woolard, Weidong Zhang

Proceedings Volume 8261, 82610B (2012) https://doi.org/10.1117/12.915985

KEYWORDS: Terahertz radiation, Doping, Heterojunctions, Indium arsenide, Mirrors, Absorption, Quantum cascade lasers, Diodes, Polarization, Resonators

Read Abstract +

Proceedings Article | 18 February 2011 Paper

THz lasing concepts based upon InAs/GaSb broken-gap heterostructures

Dwight Woolard, Weidong Zhang

Proceedings Volume 7938, 79380C (2011) https://doi.org/10.1117/12.881254

KEYWORDS: Terahertz radiation, Heterojunctions, Gallium antimonide, Phonons, Indium arsenide, Semiconductor lasers, Quantum efficiency, Acoustics, Diodes, Doping

Read Abstract +

Proceedings Article | 9 September 2010 Open Access

Molecular-level engineering of THz/IR-sensitive materials for future biological sensing application

Dwight Woolard, Gregory Recine, Alexei Bykhovski, Weidong Zhang

Proceedings Volume 7763, 77630D (2010) https://doi.org/10.1117/12.865580

KEYWORDS: Molecules, Biosensing, Switches, Molecular biology, Dielectrics, Absorption, Terahertz radiation, Carbon, Chemical species, Biological and chemical sensing

Read Abstract +

DOWNLOAD PAPER

Proceedings Article | 8 May 2006 Paper

An optically triggered I-RTD hybrid device for continous-wave generation of THz oscillations

Dwight Woolard, Weidong Zhang, Elliott Brown, Boris Gelmont, Robert Trew

Proceedings Volume 6212, 621207 (2006) https://doi.org/10.1117/12.665820

KEYWORDS: Gallium, Gallium antimonide, Oscillators, Indium gallium arsenide, Terahertz radiation, Diodes, Semiconductors, Interfaces, Chromium, Hybrid optics

Read Abstract +

Proceedings Article | 5 November 2005 Paper

A novel I-RTD based optically pulsed hybrid device for generating THz oscillations

Weidong Zhang, Dwight Woolard, Elliott Brown, Boris Gelmont

Proceedings Volume 5995, 59950S (2005) https://doi.org/10.1117/12.630570

KEYWORDS: Diodes, Oscillators, Terahertz radiation, Hybrid optics, Indium arsenide, Electron transport, Rhodium, Photons, Resistance, Transient nonlinear optics

Read 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.

Showing 5 of 6 publications

View contact details

UPDATE YOUR PROFILE

Is this your profile? Update it now.

Sign into your SPIE.org account

Don’t have a profile and want one?

Create an account on SPIE.org

Keywords/Phrases

Search In:

Publication Years