September 30, 2009

Lehigh University

Electrical and Computer Engineering Seminar Series

Fall 2009

A parametric terahertz beam generator and high sensitivity detectors for remote sensing application

Dr. Dong Ho Wu

Naval Research Lab

Wednesday, September 30 at 4pm to 5pm, Sinclair Auditorium

Abstract:

Terahertz remote-sensing applications require high sensitivity detectors and high-power terahertz sources, since terahertz signals can be quickly attenuated by water molecules present in the target, as well as in the environment between the source and the target. Of the many terahertz source technologies available, the one based on the optical parametric technique seems to be the most promising as it is portable and can produce a relatively high-power terahertz beam. In this talk I will present our new technique for the terahertz parametric oscillator (TPO), in which we recycle the pump beam in order to increase the efficiency and enhance the terahertz beam output. In our experiments the pump (Nd:YAG Q-switched) laser beam is injected into a doped LiNbO3 crystal with 5% MgO, and the exiting pump beam is redirected back through the nonlinear crystal. Our data show that the terahertz beam output power increases almost four times in magnitude, when the pump beam is recycled once in crossed-beam geometry. Also I will briefly present our research efforts for the development of three different terahertz detectors based on electro-optic (EO), metal-semiconductor-field-effect-transistor (MESFETs) and quantum dot technologies. The sensitivities of these detectors are 10-12 W/(Hz)1/2 for EO detector, 10−8 W/Hz1/2 for MESFET and 10-21 W/(Hz)1/2 for quantum dot detector. While former two can be operated at room temperature, the latter needs to be operated at temperatures below 4.2K.


Dong Ho Wu’s Biography:

Undergraduate Institution: Sung Kyun Kwan University, Seoul, Korea. Major: Physics. B.S. 1981.

July 1981-Aug. 1984    Researcher, Korea Standards Research Institute (Korean counterpart of NIST), S. Korea

Graduate Institution:  Korea Advanced Institute of Science and Technology (KAIST), Tufts University, Medford,

MA. Major: Physics. Ph.D. 1991, M.S. 1986.

Postdoctoral Institutions: Northeastern University, Boston, MA. Area: Physics. Jan.1991-July 1991.

University of Maryland, College Park, MD. Area: Physics. Aug.1991-July1993.

Appointments

May 1991 - Aug. 1991 Member of Technical Staff, GTE Laboratories, Waltham, MA.

July 1993 - Feb. 2001   Assistant Research Scientist, University of Maryland, College Park, MD

Feb. 2001 - Present,      Research Physicist (Group Leader), Naval Research Laboratory, Washington, DC.

Sept.2003 - Present,      Adjunct Professor of Physics, Temple University, Philadelphia, PA.

Publications Published 2 book contributions and 46 papers in peer reviewed journals, such as Physical Review Letters, Applied Physics Letters etc.

Inventions 5 invention disclosures and 3 patent pending

Research

Earlier research areas include high frequency superconductivity and wave (quantum) chaos.

Currently carrying out 5 projects in terahertz, electro-magneto optics, quantum dot and quantum (wave) chaos areas.