140 research outputs found
Opto-thermal transport engineering in hybrid organic-inorganic lead halide perovskites metasurfaces
Halide perovskites have recently gained widespread attention for their
exceptional optoelectronic properties which have been illuminated by extensive
spectroscopic investigations. In this article, nanophotonic surface-engineering
using soft-lithography has been used to reproduce nanostructures with enhanced
functionalities. A non-invasive optical technique based on Raman and
photolumines-cence (PL) spectroscopy is employed to investigate the interactive
effect of the thermal and optical behaviour in surface-patterned hybrid
organic-inorganic halide perovskite thin films. The thermophys-ical properties
of the engineered perovskite films are extracted from the softening of the
representa-tive peak positions in the Raman and PL spectra of the samples which
act as temperature markers. The investigation suggests a comparatively higher
rise in the local temperature for the patterned thin films resulting from their
enhanced absorption. Therefore, a cross-talk between the opto-thermal transport
phenomena in imprinted perovskite thin films pertaining to both enhancing
device properties along with maintaining device stability is established
Inversionless gain in a lossy medium
We study gain without inversion due to coherence effects in a
Doppler-broadened degenerate three-level system of a rubidium-hydrogen mixture
in a miniaturized micron scale custom vapor cell. The cell miniaturization
gives rise to collisions of atoms with the walls of the cell. This, combined
with the high collision rate with the hydrogen buffer gas allows us to observe
gain in the absorption spectra. Furthermore, we analyze the role of cell
miniaturization in the evolution of the gain profile. In addition to
fundamental interest, the observation of gain without inversion in our
miniaturized cells paves the way for applications such as miniaturized lasers
without inversion.Comment: 15 pages, 8 figures, 1 tabl
England’s Abberley-Malvern Hills Geopark as a Tourism Project
The welfare initiative has led to a creation of Abberley-Malvern Hills Geopark in the borderland of West England and Wales. It covers places of a very long geological profi le with many geosites. They are a base for a development of tourism and educational activity. It resulted in many entertainments, meetings and publications as well as new elements of tourist management, of course. Many solutions can be used for a work of Polish geoparks
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