21 research outputs found
Spectral engineering with multiple quantum well structures
It is shown that it is possible to significantly modify optical spectra of
Bragg multiple quantum well structures by introducing wells with different
exciton energies. The reflection spectrum of the resulting structures is
characterized by high contrast and tuning possibilities
Scaling and the center of band anomaly in a one-dimensional Anderson model with diagonal disorder
We resolve the problem of the violation of single parameter scaling at the
zero energy of the Anderson tight-binding model with diagonal disorder. It
follows from the symmetry properties of the tight-binding Hamiltonian that this
spectral point is in fact a boundary between two adjacent bands. The states in
the vicinity of this energy behave similarly to states at other band
boundaries, which are known to violate single parameter scaling.Comment: revised version, 4 pages, 2 figures, revte
Scaling in the one-dimensional Anderson localization problem in the region of fluctuation states
We numerically study the distribution function of the conductivity
(transmission) in the one-dimensional tight-binding Anderson model in the
region of fluctuation states. We show that while single parameter scaling in
this region is not valid, the distribution can still be described within a
scaling approach based upon the ratio of two fundamental quantities, the
localization length, , and a new length, , related to the
integral density of states. In an intermediate interval of the system's length
, , the variance of the Lyapunov exponent does not
follow the predictions of the central limit theorem, and may even grow with
.Comment: Phys. Rev. Lett 90, 126601 (2003) 4 pages, 3 figure
Scaling Properties of 1D Anderson Model with Correlated Diagonal Disorder
Statistical and scaling properties of the Lyapunov exponent for a
tight-binding model with the diagonal disorder described by a dichotomic
process are considered near the band edge. The effect of correlations on
scaling properties is discussed. It is shown that correlations lead to an
additional parameter governing the validity of single parameter scaling.Comment: 5 pages, 3 figures, RevTe
Optical properties of 1D photonic crystals based on multiple-quantum-well structures
A general approach to the analysis of optical properties of photonic crystals
based on multiple-quantum-well structures is developed. The effect of the
polarization state and a non-perpendicular incidence of the electromagnetic
wave is taken into account by introduction of an effective excitonic
susceptibility and an effective optical width of the quantum wells. This
approach is applied to consideration of optical properties of structures with a
pre-engineered break of the translational symmetry. It is shown, in particular,
that a layer with different exciton frequency placed at the middle of an MQW
structure leads to appearance of a resonance suppression of the reflection.Comment: 9 pages, 3 figures, submitted to PR
Effects of inhomogeneous broadening on reflection spectra of Bragg multiple quantum well structures with a defect
The reflection spectrum of a multiple quantum well structure with an inserted
defect well is considered. The defect is characterized by the exciton frequency
different from that of the host's wells. It is shown that for relatively short
structures, the defect produces significant modifications of the reflection
spectrum, which can be useful for optoelectronic applications. Inhomogeneous
broadening is shown to affect the spectrum in a non-trivial way, which cannot
be described by the standard linear dispersion theory. A method of measuring
parameters of both homogeneous and inhomogeneous broadenings of the defect well
from a single CW reflection spectrum is suggested.Comment: 27 pages, 6 eps figures; RevTe