Atom Based Self-Calibrating E-field Sensors and Probes: The Next Generation in Field Measurements
Dr. Chrstopher L. Holloway
National Institute of Standards and Technology
Thursday, January 16, 2014|
5:00pm - 6:00pm
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About the Event
We present a significantly new approach for an electric (E) field probe. The probe is based on the interaction of RF-fields with Rydberg atoms, where alkali atoms are excited optically to Rydberg states and the applied RF-field alters the resonant state of the atoms. For this probe, the Rydberg atoms are placed in a glass vapor cell. This vapor cell acts like an RF-to-optical transducer, converting an RF E field to an optical frequency response. The probe utilizes the concept of Electromagnetic Induced Transition (EIT), where the RF transition in the four-level atomic system causes a split of the transition spectrum for the pump laser. This splitting is easily measured and is directly proportional to the applied RF field amplitude. Therefore, by measuring this splitting we get a direct measurement of the RF E-field strength. The significant dipole response of Rydberg atoms over the GHz regime suggests this technique could allow traceable measurements over a large frequency band including 1-10000 GHz. This new approach for E-field measurements has the following benefits: 1) it will allow direct SI units linked E--field measurements (currently not possible), 2) it will be self-calibrating based on calculable atomic resonances (calibration costs will be eliminated), 3) it will not perturb the field during the measurement (no metal is present in the sensor head), 4) it will have significantly improved sensitivity over current E-field sensors (<1 mV//m, two orders of magnitude improvement over current approaches,<1 0 1V/m may be possible), 55) it will have expanded band width versus current technologies allowing measurements over 1-500 GHz and possibly up to 1 THz, and 6) the sensor will be a very small and compact (tens of mm to a few mm versus tens of cm). Possible applications for this probe are numerous, ranging from spectrum measurement, to biomedical, to sub-wavelength imaging.. This talk will summarize the theory behind the new approach, show initial results, discuss uncertainties in this type of measurement, and discuss various applications.
Christopher L. Holloway (Sྒ-M鯲-SMཀ-F’10) is a Fellow o f the IEEE and received thee B.S. degree from the University of Tennessee at Chattanooga, and thee M.S. and Ph.D. degrees from the University of Colorado at Boulder, both in electrical engineering. During 1992 he was a Research Scientist with Electro Magnetic Applications, Inc., in Lakewood, Co. From the fall of 1992 to 1994 he was with the National Center for Atmospheric Research (NCAR) in Boulder, Co. While at NCAR his duties included wave propagation modeling, signal processing studies, and radar systems design. From 1944 to 2000 he was with the Institute for Telecommunication Sciences (ITS) at t he U.S. Department of Commerce in Boulder, Co., where he was involved in wave propagation studies. Since 2000 he has been with the National Institute of Standards and Technology (NIST), Boulder, CO, where he works on electromagnetic theory. He is also on the Graduate Faculty at the University of Colorado at Boulder. Dr. Holloway received the 2013 IEEE APS Society Edward E. Altshuler Award, 2008 IEEE EMC Society Richard R. Stoddart Award, the 2006 Department of Commerce Bronze Medal for his work on radio wave propagation, the 1999 Department of Commerce Silver Medal for his work in electromagnetic theory, and the 19998 Department of Commerce Bronze Medal for his work on printed circuit boards. Dr. Holloway is currently serving as chair for US Commission A of the International Union of Radio Science and is an Associate Editor for the IEEE Transactions on Electromagnetic Compatibility. He has published over 200 technical articles including: 92 refereed journal articles, 105 conference papers, 77 conference presentations without publications, 2 book chapters, and 31 technical reports. Dr. Holloway’s research interests include electromagnetic field theory, wave propagation, guided wave structures, remote sensing, numerical methods, metamaterials, measurement techniques, EMC/EMI issues, and atom based metrology.
Contact: Karla Johnson
Sponsor: IEEE Southeastern Michigan Section Chapter
Open to: Public