311 research outputs found
Evidence for Braggoriton Excitations in Opal Photonic Crystals Infiltrated with Highly Polarizable Dyes
We studied angle-dependent reflectivity spectra of opal photonic crystals
infiltrated with cyanine dyes, which are highly polarizable media with very
large Rabi frequency. We show that when resonance conditions between the
exciton-polariton of the infiltrated dye and Bragg frequencies exist, then the
Bragg stop band decomposes into two reflectivity bands with a semi-transparent
spectral range in between that is due to light propagation inside the gap
caused by the existence of braggoriton excitations. These novel excitations
result from the interplay interaction between the Bragg gap with spatial
modulation origin and the polariton gap due to the excitons, and may lead to
optical communication traffic inside the gap of photonic crystals via channel
waveguiding.Comment: LaTex, 5 pages, 3 figures include
Anomalous Coherent Backscattering of Light from Opal Photonic Crystals
We studied coherent backscattering (CBS) of light from opal photonic crystals
in air at different incident inclination angles, wavelengths and along various
[hkl] directions inside the opals. Similar to previously obtained CBS cones
from various random media, we found that when Bragg condition with the incident
light beam is not met then the CBS cones from opals show a triangular line
shape in excellent agreement with light diffusion theory. At Bragg condition,
however, we observed a dramatic broadening of the opal CBS cones that depends
on the incident angle and [hkl] direction. This broadening is explained as due
to the light intensity decay in course of propagation along the Bragg direction
{\em before the first} and {\em after the last} scattering events. We modified
the CBS theory to incorporate the attenuation that results from the photonic
band structure of the medium. Using the modified theory we extract from our CBS
data the light mean free path and Bragg attenuation length at different [hkl].
Our study shows that CBS measurements are a unique experimental technique to
explore photonic crystals with disorder, when other spectroscopical methods
become ambiguous due to disorder-induced broadening.Comment: 10 pages, 5 figure
Observation of inhibited spontaneous emission and stimulated emission of rhodamine 6G in polymer replica of synthetic opal
This article may be downloaded for personal use only. Any other use requires prior permission of the author and AIP Publishing. This article appeared in K. Yoshino, S. B. Lee,b) S. Tatsuhara, Y. Kawagishi, and M. Ozaki, and A. A. Zakhidov, Appl. Phys. Lett. 73, 3506 (1998) and may be found at https://doi.org/10.1063/1.122819
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