[Faculty] Fwd: [CSRC.COLLOQUIUM] "Exceptional points of degeneracy in electromagnetic, electronic and photonic systems: Theory and applications"

[Jose Castillo]

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DATE:
*Friday, October 14, 2022*


TITLE:
*Exceptional points of degeneracy in electromagnetic, electronic and
photonic systems: Theory and applications*



TIME:
*3:30-4:30PM*



LOCATION:
*In Person - GMCS 314*


SPEAKER/BIO:
*Filippo Capolino, Electrical Engineering and Computer Science, UC Irvine*



ABSTRACT:
There are various kinds of degeneracies in systems and we discuss an
important class of them: the case when two or more eigenstates of a system
coalesce. Such degeneracies can happen in any kind of system: we will
present a general theory but focus on cases of circuits, resonators (i.e.,
coupled LC resonators, electromagnetic cavities, optical ring resonators,
etc.), multimode waveguides and other optical systems. This kind of
exceptional degeneracy that involves also the polarization states, can
happen in a surprisingly large number of systems. Such degeneracies occur
in systems that can be fully passive or in systems that include gain
elements; we discuss the common aspects of these two classes. The number of
coalescing eigenmodes determines the order of the degeneracy. We will
discuss the role of symmetries in the occurrence of exceptional points of
degeneracy (EPDs) in waveguides.

For example, we explore the concept of array of antennas arranged
periodically and sequentially fed by two coupled transmission lines. We
investigate different radiating array structures capable of exhibiting EPDs
in their dispersion diagram. We will explore a few kinds of EPDs called,
the regular band edge, the stationary inflection point, and the degenerate
band edge, etc.

We will also provide various experimental verifications of the occurrence
of EPDs in resonators and waveguides. We will discuss possible applications
in oscillators, antenna arrays, amplifiers, delay lines, etc.

In the second part of the talk we will discuss how the concept of EPD is
useful to conceive very high sensitive systems that can pave the way to a
new scheme of highly-sensitive sensors. Indeed, it has been apparent that
resonant frequencies in a system with EPD are extremely sensitive to a
perturbation. Therefore, the detection of a frequency shift in a resonator
or in an oscillator based on EPD is an indicator of an applied physical,
chemical or biological perturbation. Systems of EPDs can be realized using
gain and loss (usually referred as EPDs induced in PT symmetric systems),
time modulation of a component, etc. We will provide the experimental
demonstration of such extremely sensitive systems.

Bio: Filippo Capolino received the Ph.D. degree in electrical engineering
from the University of Florence, Italy, in 1997. He is currently a
Professor with the Department of Electrical Engineering and Computer
Science at the University of California, Irvine, CA, USA. Previously he has
been an Assistant Professor at the Department of Information Engineering at
the University of Siena, Italy. From 1997 to 1999, he was a Fulbright
Scholar and Postdoctoral Fellow with the Department of Aerospace and
Mechanical Engineering, Boston University, MA, USA. From 2000 to 2001, part
of 2005 and in 2006, he was a Research Assistant Visiting Professor with
the Department of Electrical and Computer Engineering, University of
Houston, TX, USA. He has been a short term Visiting Professor at the
Fresnel Institute, Marseille, France (2003) and at the Centre de Recherche
Paul Pascal, Bordeaux, France (2010).  From Jan. to Jun. 2022 he hold a
Cathedra of Excellence at the University of Carlos III, Madrid, Spain.

His research interests include applied electromagnetics in general, sensors
in both microwave and optical ranges, photonics, microscopy, metamaterials
and their applications, traveling wave tubes, antennas, propagation,
wireless systems, chip-integrated systems, etc. He is an IEEE Fellow, and
he is the editor of the two volume “Metamaterials Handbook”.


Host:
*Jose Castillo*

Note: Videos of previous colloquium talks can be seen on the CSRC website
in the colloquium archive section or on the CSRC YouTube page here
<https://www.youtube.com/channel/UCN0ZEztlmyDqG2pm-Rle_Eg/feed>.




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