From billiards for light to light in mesoscopic systems
| When |
May 22, 2018
from 10:45 to 12:00 |
|---|---|
| Where | salle des thèses |
| Attendees |
Martina Hentschel |
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The investigation of the propagation of light in mesoscopic, i.e. often micrometer-scale, systems is a rich subject providing insights ranging from quantum chaos in open systems to new schemes for realizing microlasers. The concept of quantum-classical, here wave-ray, correspondence, proves to be as useful as for electronic mesoscopic systems such as quantum dots. Whereas there the electrons are confined by means of gate voltages, the confinement of light in optical microresonators is due to total internal reflection, leading to billiards for light. There are, however, semiclassical deviations from the naive ray-picture expectation in the reflection and refraction of light at dielectric interfaces yielding for example to deviations from Snell's law. We illustrate these effects and discuss their impact on the far-field emission characteristics of optical microcavities.
The propagation of electromagnetic waves in three-dimensional optical microcavities requires to pay attention to the evolution of the light's polarization as a new degree of freedom. In systems like dielectric Möbius-strips or cone-shaped microtube cavities, the polarization state of resonant whispering gallery-type modes may differ strongly from the reference case of homogeneous cylinders. Whereas we find that the polarization of the electromagnetic field follows the wall orientation in thin Möbius strips, thereby reflecting the accumulated geometric phase, we observe that the electromagnetic field ignores the Möbius topology when the strip thickness is increased. Breaking of symmetries further influences the morphology of resonances and can induce a transition from linear to elliptical polarization that is both of theoretical interest from the point of view of spin-orbit interaction of light and their interpretation in terms of Berry phases, and relevant for potential applications.