Welcome to RMOSA! Join us for seminars devoted to optical science, technology, and industry.

Join us on May 17, 2012 -- 15 minutes earlier than usual for our year-end pizza dinner, followed by our featured speaker.

Our next seminar

"Superconducting devices for detection of single photons"

Speaker: Dr. Sae Woo Nam, NIST
Date: Thursday, May 17, 2012
Time: Pizza dinner - 6:45 p.m. (Koelbel Building Downstairs), Seminar - 7:30 p.m.
Where: Room 340, Koelbel Building, Leeds School of Business on the CU Boulder Campus.
Parking: Parking on Regent Dr. is free after 5 p.m.; the entire lot in front of Koelbel is available to the public for a small fee at either of the two pay stations in the lot.
Map to Venue: http://www.colorado.edu/campusmap/map.html?bldg=KOBL

Abstract:
There is increasing interest in using superconducting optical photon detectors in a variety of applications. These applications require detectors that have extremely low dark count rates, high count rates, and high quantum efficiency. I will describe our work on two types of superconducting detectors, the Nanowire Superconducting Single Photon Detector (nSSPD) and superconducting Transition-Edge Sensor (TES). A nSSPD is an ultra-thin, ultra-narrow (nm scale) superconducting meander that is current biased just below its critical current density. When one or more photon is absorbed, a hot spot is formed that causes the superconductor to develop a resistance and consequently a voltage pulse. By exploiting the sharp superconducting-to-normal resistive transtion of tungsten at 100mK, TES detectors give an output signal that is proportional to the cumulative energy in an absorption event. This proportional pulse-height enables the determination of the energy absorbed by the TES and the direct conversion of sensor pulse-height into photon number. I will discuss our progress towards developing detectors with quantum efficiencies approaching 100% as well as describe applications that are enhanced by using these detectors.

Bio:
Dr. Sae Woo Nam attended the Massachusetts Institute of Technology, where he received a degree in Physics and a degree in Electrical Engineering in 1991. He did his graduate studies at Stanford University where he received two degrees in physics: M.S. (1998) and Ph.D. (1998). Following his degree, he was awarded an NRC Postdoctoral Fellowship at NIST to work on advanced applications of superconducting transition-edge sensor (TES) based detectors. The applications have included development of a high-energy resolution x-ray detector system which is being commercialized and the development of an advanced detector readout scheme is being used in ground-based sub-mm telescopes (e.g. SCUBA2). Presently, Dr. Nam is a staff scientist at NIST and is the project leader for the Quantum information and terahertz technology project in the Physical Measurements Laboratory at NIST. He has been involved (both at Stanford and NIST) with developing superconducting devices to detect optical photons. He has also built prototype detector systems that have been involved in the first demonstrations of the use of superconducting devices in quantum information applications such as quantum key distribution and single photon source and entangled photon source characterizations. Dr. Sae Woo Nam received a 2002 PECASE (Presidential Early Career Award for Scientists and Engineers) for work on advanced photon detectors and contributions to the field of primary thermometry using Johnson noise, and was recently made an OSA fellow.

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