692 research outputs found
Room temperature midinfrared electroluminescence from GaInAsSbP light emitting diodes. .
Room temperature electroluminescence in the midinfrared near 4 µm is reported from GaInAsSbP light emitting diodes grown on GaSb by liquid phase epitaxy. Comparison of the electro- and photoluminescence revealed that light is generated on the p side of the diode. The energy shift (24 meV) is consistent with band gap narrowing and recombination via band tail states due to the Zn doping (1×1018 cm−3) in the p layer of the structure. The temperature dependent behavior of the luminescence and the improved emission intensity was attributed to recombination from localized states arising from electrostatic potential fluctuations due to compositional inhomogeneities in these alloys
Tangled nonlinear driven chain reactions of all optical singularities
Dynamics of polarization optical singularities chain reactions in generic
elliptically polarized speckle fields created in photorefractive crystal LiNbO3
was investigated in details Induced speckle field develops in the tens of
minutes scale due to photorefractive 'optical damage effect' induced by
incident beam of He-Ne laser. It was shown that polarization singularities
develop through topological chain reactions of developing speckle fields driven
by photorefractive nonlinearities induced by incident laser beam. All optical
singularities (C points, optical vortices, optical diabolos,) are defined by
instantaneous topological structure of the output wavefront and are tangled by
singular optics lows. Therefore, they have develop in tangled way by six
topological chain reactions driven by nonlinear processes in used nonlinear
medium (photorefractive LiNbO3:Fe in our case): C-points and optical diabolos
for right (left) polarized components domains with orthogonally left (right)
polarized optical vortices underlying them. All elements of chain reactions
consist from loop and chain links when nucleated singularities annihilated
directly or with alien singularities in 1:9 ratio. The topological reason of
statistics was established by low probability of far enough separation of born
singularities pair from existing neighbor singularities during loop
trajectories. Topology of developing speckle field was measured and analyzed by
dynamic stokes polarimetry with few seconds' resolution. The hierarchy of
singularities govern scenario of tangled chain reactions was defined. The
useful space-time data about peculiarities of optical damage evolution were
obtained from existence and parameters of 'islands of stability' in developing
speckle fields.Comment: 11 pages, 12 figure
The Cosmological Gene Project: cluster analysis of the atmospheric fluctuations on arcmin-scale imaging of the Cosmic Microwave Background
We discuss some aspects of the Cosmological Gene Project started at the
Special Astrophysical Observatory (Russia) in 1999. The goal of the project is
to measure the anisotropy and polarization of the Cosmic Microwave Background
(CMB) and investigation of atmospheric fluctuations and foreground on
arcmin-scales using the radio-telescope RATAN-600. We develop the cluster
analysis of one-dimensional random fields for the application to the RATAN-600
scans. We analyze the specific properties of peak clusterisation in the
RATAN-600 scans which to separate the primordial CMB signal from noise.Comment: Submitted to Astronomy & Astrophysic
- …