Unit:
Κατεύθυνση Φυσική των ΥλικώνLibrary of the School of Science
Supervisors info:
Κοσμάς Τσακμακίδης, Επίκουρος Καθηγητής, Τομέας Φυσικής Στερεάς Κατάστασης
Δημοσθένης Σταμόπουλους, Αναπληρωτής Καθηγητής, Τομέας Φυσικής Συμπυκνωμένης Ύλης
Σπυρίδων Γαρδέλης, Αναπληρωτής Καθηγητής, Τομέας Φυσικής Συμπυκνωμένης Ύλης
Original Title:
Μελέτη με τη μέθοδο των πεπερασμένων διαφορών στο πεδίο του χρόνου (FDTD) γρήγορου φωτός σε μέσα με διασπορά
Translated title:
FDTD studies of "fast light" in dispersive media.
Summary:
The objective of the present study (thesis) was to study “fast light” in amplifying active
media, i.e., the behavior of the propagation of a pulse during its transit through a medium
with gain in which, both, amplification and development of a negative group velocity occur.
First, we shall concisely review the basic theory of active dispersive media as related to
their properties with an extensive reference to their dielectric function. Afterwards, we
shall focus on the wave nature of a pulse and its interaction with such a medium, focusing
on an analysis of the behavior of the group velocity in a medium giving rise to, so called,
“fast light” (group velocity vg larger than the speed of light in vacuum c, or vg negative). In
those cases, we also study the propagation of energy and its velocity in the “fast light”
medium, and it is explained that in all cases relativistic causality is strictly obeyed.
We then concisely review the basics of the Finite-Difference Time-Domain (FDTD) method
in one dimension, outlining the basic algorithmic processes that govern it, its basic
characteristics related to its stability, the introduction of sources, numerical dispersion
aspects, and the necessity for absorbing conditions. We proceed by detailing results of our
simulations of “fast light” in dispersive active media on the basis of the one-dimensional
FDTD method. Analytical tools elucidate the above phenomena theoretically, following
which we verify them using the FDTD method. At the end, follows a comparison of the two
approaches (analytical and numerical) and an attempt to explain ensuing differences
resulting from their use.
Main subject category:
Science
Keywords:
FDTD, active media, dispersive media, group velocity, signal velocity, fast light, slow light, finite difference time domain, gain media
File:
File access is restricted only to the intranet of UoA.
diploma.pdf
1 MB
File access is restricted only to the intranet of UoA.
