Black-hole waves at a conical tip of negative material

Add to your list(s) Download to your calendar using vCal

• Anne-Sophie Bonnet-Ben Dhia (ENSTA ParisTech)
• Friday 10 February 2023, 09:45-10:30
• Seminar Room 1, Newton Institute.

If you have a question about this talk, please contact nobody.

MWSW01 - Canonical scattering problems

This is a work in collaboration with Mahran Rihani and Lucas Chesnel. We are interested in time-harmonic electromagnetic waves in a medium where the dielectric permittivity is supposed to be real-valued and piecewise constant, with both positive and negative values. Such model is relevant for instance when considering  metal-dielectric interfaces at optical frequencies. Due to the sign change of the permittivity, so-called plasmonic waves can travel at the surface of the metal. More specifically, this talk concerns configurations where the surface of the metal has a geometric singularity which coincides locally with a conical tip (not necessarily circular). Then a very strange phenomenon occurs. Some plasmonic waves travel towards the tip, slowing down more and more, so that they never reach the tip. These so-called black-hole waves result in a hyper-oscillating behavior of the electric field which is non longer square-integrable, because of the energy accumulated in the vicinity of the tip. Black-hole waves are linked to the solutions of a transmission problem for the Laplace equation for the infinite conical tip, with sign-changing coefficients. After a separation of variables, one has to study an eigenvalue problem set on the sphere. The difficulty comes from the sign-change of the coefficients which makes it non-selfadjoint. During the talk, we will give a survey of the theoretical, analytical and numerical results that have been proved for this unusual spectrum.

This talk is part of the Isaac Newton Institute Seminar Series series.

This talk is included in these lists:

• All CMS events
• Featured lists
• INI info aggregator
• Isaac Newton Institute Seminar Series
• School of Physical Sciences
• Seminar Room 1, Newton Institute
• bld31

Note that ex-directory lists are not shown.