<div dir="ltr"><br clear="all"><div><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div dir="ltr"><div><div dir="ltr"><div><br></div></div></div></div></div></div></div></div><div class="gmail_quote"><br><div><div><p><img alt="SDSU_CSRC Logo.jpg" width="534px" height="107px" src="cid:ec3f59fd-9a31-4c13-85de-2d8ef1be2a7a"><br></p><p><br></p><p><font size="4">DATE: <br><b>Friday, October 14, 2022</b></font></p><p><br></p><div dir="ltr"><p></p><p></p><p><font size="4">TITLE:<br><b>Exceptional points of degeneracy in electromagnetic,
electronic and photonic systems: Theory and applications</b> </font><b> </b> <b> </b></p><p><b> </b></p><p><font size="4">TIME: <br><b>3:30-4:30PM</b></font></p><p> <br></p><p><font size="4">LOCATION:<br><b>In Person - GMCS 314</b><br><br></font></p><p><br></p><p><font size="4">SPEAKER/BIO: <br><b>Filippo Capolino, Electrical Engineering and Computer Science, UC Irvine</b> </font><b> </b> <b> </b> <b> </b> <b> </b> <b> </b> <b> </b> <b> </b> <b> </b></p><p><br></p><p><font size="4">ABSTRACT:<br>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.</font></p><p><font size="4">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. </font></p><p><font size="4">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.</font></p><p>
<font size="4">
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. <br><br>Bio: Filippo
Capolino<b> </b>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.</font></p>
<p><font size="4">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”.</font></p><p><br></p></div><div dir="ltr"><p><font size="4">Host:<br><b>Jose Castillo</b><br></font></p></div><div><font size="4"><br></font></div><div><p><font size="4"><span style="font-weight:bold">Note:</span><span style="font-weight:bold"> </span>Videos of previous colloquium talks can be seen on the CSRC website in the colloquium archive section or on the <a href="https://www.youtube.com/channel/UCN0ZEztlmyDqG2pm-Rle_Eg/feed" target="_blank">CSRC YouTube page here</a>.</font></p><p><br></p><p><br></p></div></div><div><div></div></div></div><br>
<p></p>
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