6,632 research outputs found
Birefringence analysis of multilayer leaky cladding optical fibre
We analyse a multilayer leaky cladding (MLC) fibre using the finite element
method and study the effect of the MLC on the bending loss and birefringence of
two types of structures: (i) a circular core large-mode-area structure and (ii)
an elliptical-small-core structure. In a large-mode-area structure, we verify
that the multilayer leaky cladding strongly discriminates against higher order
modes to achieve single-mode operation, the fibre shows negligible
birefringence, and the bending loss of the fibre is low for bending radii
larger than 10 cm. In the elliptical-small-core structure we show that the MLC
reduces the birefringence of the fibre. This prevents the structure from
becoming birefringent in case of any departures from circular geometry. The
study should be useful in the designs of MLC fibres for various applications
including high power amplifiers, gain flattening of fibre amplifiers and
dispersion compensation.Comment: 18 page
Co-axial dual-core resonant leaky fibre for optical amplifiers
We present a co-axial dual-core resonant leaky optical fibre design, in which
the outer core is made highly leaky. A suitable choice of parameters can enable
us to resonantly couple power from the inner core to the outer core. In a
large-core fibre, such a resonant coupling can considerably increase the
differential leakage loss between the fundamental and the higher order modes
and can result in effective single-mode operation. In a small-core single-mode
fibre, such a coupling can lead to sharp increase in the wavelength dependent
leakage loss near the resonant wavelength and can be utilized for the
suppression of amplified spontaneous emission and thereby gain equalization of
an optical amplifier. We study the propagation characteristics of the fibre
using the transfer matrix method and present an example of each, the
large-mode-area design for high power amplifiers and the wavelength tunable
leakage loss design for inherent gain equalization of optical amplifiers.Comment: 6 page
Thermodynamic anomalies in the pressure-temperature phase diagram of poly-4-methyl pentene-1 : disordering of crystals on cooling
Highly unusual phase behavior, of general implication for condensed matter, is reported for the title polymer. In situ x-ray studies, at the prerequisite pressure and temp., reveal amorphization in this polymer, passing through a continuously varying sequence of mesomorphic states, at 2 widely sepd. temp. regions, the process being reversible. Present findings invoke the possibility of the reentrant, widely sepd. disordered phases with temp. Such possibility has risen for the 1st time in a single-component system. The pressure-induced disordered phase, obtained at room temp., converts into crystal with increasing temp. and reverts to a glassy disordered phase on lowering the temp. Other unexpected findings include a new pressure-induced modification of the polymer, with a 1-way entry only. A few aspects of similar features found in other materials are also stated. [on SciFinder (R)
Change in patient concerns following total knee arthroplasty described with the International Classification of Functioning, Disability and Health: a repeated measures design
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