IEEE NY JOINT MTT AP PHO & NANO CHAPTER - SEMINAR: Beyond CPA: A General Theory of Reflectionless Scattering

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We invite you to a lecture by prof. A. Douglas Stone (Yale University)


Abstract – Over a decade ago the phenomenon of coherent perfect absorption (CPA) drew attention to the existence of non-scattering or reflectionless solutions to all linear wave equations, in arbitrary dimensions and for any structure larger than the wavelength of the exciting wave. In the case of electromagnetic wave scattering these solutions were shown to be the time-reverse of a corresponding laser system at its oscillation threshold, but the phenomenon is even more general and has been observed, e.g. in acoustics, AC circuits and with quantum matter waves. In CPA waves are perfectly trapped in a lossy resonator by interference and hence are ultimately completely transduced to another form of energy, without any reflected waves. However, in controlling the propagation of waves, often the goal is not transduction but to guide waves into desired output channels without any reflection back into the input channels and without any substantial loss of energy. Recently we have developed a general theory of reflectionless scattering of linear waves which encompasses both reflectionless behavior via transduction (CPA) and reflectionless behavior via perfect “forward” routing of waves, which we term Reflectionless Scattering Modes (RSMs).   This theory has the same structure and universality as does the original theory of CPA. In both cases one can show that countably infinite solutions exist at complex frequencies, and to find steady-state harmonic solutions two things are necessary: 1) A single structural or material parameter needs to be tuned to move the solution to a real frequency. 2) The appropriate input wavefront must be imposed on the structure at this frequency. An unstructured or incoherent wave at the same frequency will not be reflectionless, and even can be strongly scattered. I will review experiments which confirm both CPA and RSM at optical frequencies and other experiments at microwave frequencies which demonstrate functionalized signal routing, such a frequency demultiplexing, based on RSMs. RSMs can exhibit a novel kind of spontaneous parity-time symmetry breaking even in lossless systems, leading to novel resonance lineshapes, which were previously observed by not fully understood.



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  • Date: 08 Dec 2023
  • Time: 10:00 AM to 11:30 PM
  • All times are (UTC-05:00) Eastern Time (US & Canada)
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This is an in-person seminar. If you opt to join via zoom use meeting ID 848 8975 0947, Passcode 412414

  • 85 SAINT NICHOLAS TERRACE
  • New York, New York
  • United States 10031
  • Building: ASRC
  • Room Number: 1st Floor Auditorium
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  • Co-sponsored by Advanced Science Research Center - the Graduate Center - City University of New york
  • Starts 01 December 2023 01:00 AM
  • Ends 08 December 2023 05:00 PM
  • All times are (UTC-05:00) Eastern Time (US & Canada)
  • No Admission Charge


  Speakers

A.Douglas Stone of Yale University

Topic:

Beyond CPA: A General Theory of Reflectionless Scattering

Bio – A. Douglas Stone is the Carl Morse Professor of Applied Physics and Physics at Yale University. He was the 2014 recipient of the Phi Beta Kappa Award in Science for his book Einstein and the Quantum: The Quest of the Valiant Swabian. He has a Ph.D. in Physics from MIT, a social studies degree from Harvard and degrees in physics and philosophy from Oxford University. He was a Rhodes Scholar in 1976, An Alfred P. Sloan Fellow in 1990, an American Physical Society Fellow in 1993 and a fellow of the Optical Society of America in 2010.

Biography:

Bio – A. Douglas Stone is the Carl Morse Professor of Applied Physics and Physics at Yale University. He was the 2014 recipient of the Phi Beta Kappa Award in Science for his book Einstein and the Quantum: The Quest of the Valiant Swabian. He has a Ph.D. in Physics from MIT, a social studies degree from Harvard and degrees in physics and philosophy from Oxford University. He was a Rhodes Scholar in 1976, An Alfred P. Sloan Fellow in 1990, an American Physical Society Fellow in 1993 and a fellow of the Optical Society of America in 2010.