219 research outputs found
All-optical measurement of elastic constants in nematic liquid crystals
In this article we present a new all-optical method to measure elastic constants connected with twist and bend deformations. The method is based on the optical Freedericksz threshold effect induced by the linearly polarized electro-magnetic wave. In the experiment elastic constants are measured of commonly used liquid crystals 6CHBT and E7 and two new nematic mixtures with low birefringence. The proposed method is neither very sensitive on the variation of cell thickness, beam waist or the power of a light beam nor does it need any special design of a liquid crystal cell. The experimental results are in good agreement with the values obtain by other methods based on an electro-optical effect
Solitons in coupled atomic-molecular Bose-Einstein condensates in a trap
We consider coupled atomic-molecular Bose-Einstein condensate system in a
quasi-one-dimensional trap. In the vicinity of a Feshbach resonance the system
can reveal soliton-like behavior. We analyze bright soliton solutions for the
system in the trap and in the presence of the interactions between particles.
We show that with increasing number of particles in the system two bright
soliton solutions start resembling dark soliton profiles known in an atomic
Bose-Einstein condensate with repulsive interactions between atoms. We analyze
also methods for experimental preparation and detection of the soliton states.Comment: 7 pages, 7 figures, published versio
Terahertz Radiation Detection by Field Effect Transistor in Magnetic Field
We report on terahertz radiation detection with InGaAs/InAlAs Field Effect
Transistors in quantizing magnetic field. The photovoltaic detection signal is
investigated at 4.2 K as a function of the gate voltage and magnetic field.
Oscillations analogous to the Shubnikov-de Haas oscillations, as well as their
strong enhancement at the cyclotron resonance, are observed. The results are
quantitatively described by a recent theory, showing that the detection is due
to rectification of the terahertz radiation by plasma waves related
nonlinearities in the gated part of the channel.Comment: 4 pages, 3 figure
Nonlinear directional coupler for polychromatic light
We demonstrate that nonlinear directional coupler with special bending of
waveguide axes can be used for all-optical switching of polychromatic light
with very broad spectrum covering all visible region. The bandwidth of
suggested device is enhanced five times compared to conventional couplers. Our
results suggest novel opportunities for creation of all-optical logical gates
and switches for polychromatic light with white-light and super-continuum
spectrum.Comment: 3 pages, 3 figure
Wykorzystanie modelowania geochemicznego oraz badań izotopowych siarczanów do identyfikacji procesów kształtujących skład chemiczny wód podziemnych ujęcia Gliwice-Łabędy
In order to determine geochemical processes affecting chemical composition of groundwater in the Gliwice-Łabędy
well-field area two research methods were applied. Chemical analysis allowed us to assess the quality of groundwater in the Triassic
karst-fractured-porous aquifer of the southwestern part of the major groundwater basin no. 330. The chemical composition of groundwater
is distinguished by spatial heterogeneity highlighted by higher mineralization and concentrations of individual ions in the western
area. In addition, all samples collected in 2016 were analyzed for the 34S and 18O to identify sources of sulfates in the waters examined.
The study revealed a different origin of these ions depending on location of the wells sampled. The results of chemical analysis and
archival data allowed for application of geochemical modeling in identification of processes taking part in groundwater chemistry
evolution. Simulations of processes controlling water chemistry within the Triassic aquifer were conducted using The Geochemist’s
Workbench 10.0.6. The examined processes encompassed dissolution of minerals forming the carbonate aquifer and Miocene evaporates
overlying the Triassic aquifer as well as mixing of groundwater and surface water
Proceedings of the XXXVI International School of Semiconducting Compounds
The new approach to the understanding of intrashallow donor transition in the reduced dimensionality systems is presented. The magnetospectroscopy experiments done on the CdTe/CdMgTe quantum well based samples, uniformly n-doped, show indications that the surprising lack of spectral sensitivity on applied photon energy can be understood as a result of sample response coming from its different regions. This "non spectroscopic" behaviour (in a sense of the Zeeman splitting) is a consequence of the properties of systems with reduced dimensionality where variety of centre locations in the structure results in continuous density of states available for absorption
Observation of light-induced reorientational effects in periodic structures with planar nematic-liquid-crystal defects
We report on the experimental studies of the light-induced reorientational effects in a one-dimensional periodic photonicstructure with an embedded planar nematic-liquid-crystal defect. We demonstrate that in the presence of a periodic structure, the self-action of light in a liquid-crystal layer demonstrates sharp power-dependent characteristics for the intensity-dependent optical transmission. Robustness of the effect suggests its applications for all-optical tunable photonic devices.This work was supported
by the Australian Research Council through Discovery and
Center of Excellence projects
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