Professor Emeritus of Electrical Engineering
Hans Kuehl received his BS in 1955 from Princeton University and his PhD in 1959 from the California Institute of Technology, both in electrical engineering. He served as Department Chairman from 1987 to 1998.
His most recent research interests include the study of localized nonlinear pulses called solitons in electronic plasmas and in optical fibers. Solitons have an important technological impact in the area of fiber optic communication, where light pulses in the form of solitons are used for broadband information transmission.
Professor Kuehl's major past research contributions include the formulation and development of the basic theory governing the interaction of antennas and electronic plasmas. He was elected Fellow of the Institute of Electrical and Electronics Engineers for his research in this area. He has served as a consultant for several industrial firms, including the Hughes Aircraft Co. and the Aerospace Corp.
Awards that he has received include the University of Southern California Associates Teaching Excellence Award, the USC Archimedes Circle Faculty Service Award, and the Eta Kappa Nu Outstanding Electrical Engineering Faculty Award. In addition, Professor Kuehl served as the co-chairman of the task force at USC that developed an innovative new electrical engineering curriculum that became effective in 1996. He was the lead faculty member in the development of the Web-enhanced version of the EE Department's basic circuits course. In 2006, Professor Kuehl received the USC Faculty Lifetime Achievement Award for his outstanding teaching, research and service.
Professor Kuehl's recent research thrust is the study of localized nonlinear pulses in plasmas and in optical fibers. Two important aspects of this research are the determination of the properties of laser-pulse solitary waves in a plasma, and of ion-acoustic solitary waves in a beam-plasma system. Solitary waves are important because they often have the unusual property that they travel for long distances without changing shape in a lossless, uniform environment. Solitons, which are solitary waves that retain their shape after colliding with each other, have an important technological impact in the area of fiber optic communication, where light pulses in the form of solitons are used for broadband information transmission. Solitons are also found in plasmas, fluids, crystal lattices, and nonlinear transmission lines.
The most recent research program is an analytical and numerical study of the characteristics of solitons and solitary waves in various plasma environments as well as the effect of small perturbations in the equations governing solitons. A major reason for studying perturbations on solitons and solitary waves is that in many physical systems in which the perturbation is controllable, it may be possible to adjust it in order to produce certain desired modifications of the soliton, such as reshaping, amplification, compression, or reflection. An important purpose of this research is the exploration of how the perturbation can be tailored to achieve specific soliton properties in nonlinear systems. The study of small perturbations on solitons is important because, although the effect is small, the accumulated modification of the soliton may be large when the perturbation acts over a long time period.
Professor Kuehl's major past research contributions include the formulation and development of the basic theory governing the interaction of antennas and plasmas. He was one of the first theoreticians to predict and describe in detail the phenomenon of plasma resonance cones, which produce significant enhancement of the electromagnetic fields of an antenna in a magnetized plasma. The resonance cone phenomenon plays an important role in the measurement of electron density and temperature in ionospheric and magnetospheric plasmas, and in the energy transfer of lower hybrid waves that are used for the heating of plasmas in fusion reactors.