Search results for "Dispersion."
showing 10 items of 1094 documents
Ultrahigh-birefringent squeezed lattice photonic crystal fiber with rotated elliptical air holes.
2010
We report an experimental realization of a highly birefringent photonic crystal fiber as a result of compressing a regular hexagonal structure. The experimental measurements estimate a group birefringence of approximately 5.5x10(-3) at 1550 nm in good agreement with the numerical results. We study the influence of compressing the regular structure at different directions and magnifications, obtaining a method to realistically enhance the phase birefringence while moderating the group birefringence.
Designing a photonic crystal fibre with flattened chromatic dispersion
1999
Using a full-vector modal method, the authors have identified a region of nearly zero flattened chromatic dispersion in a specially designed photonic crystal fibre. The approach permits an accurate control of the dispersion features of these fibres in terms of their structural parameters.
Optical properties of lithium gallium oxide
2017
Abstract The optical dielectric function tensor of orthorhombic single-crystal LiGaO 2 was determined for polarizations along a , b , and c crystal-axis in the photon energy range from 0.04 eV to 6.5 eV by the generalized spectroscopic ellipsometry. In the far-infrared spectral range from 12.4 meV to 40 meV, the dielectric function was determined from conventional polarized transmittance and polarized reflectance measurements. Lineshape analysis of the dielectric function tensor major components allowed for a determination of the long-wavelength optical phonon characteristics, refractive indices dispersion, and parameters of interband and excitonic optical transitions.
Efficient photoluminescent thin films consisting of anchored hybrid perovskite nanoparticles
2016
Methylammonium lead bromide nanoparticles are synthetized with a new ligand (11-aminoundecanoic acid hydrobromide) by a non-template method. Upon dispersion in toluene they show a remarkable photoluminescence quantum yield of 80%. In addition, the bifunctional ligand allows anchoring of the nanoparticles on a variety of conducting and semiconducting surfaces, showing bright photoluminescence with a quantum yield exceeding 50%. This opens a path for the simple and inexpensive preparation of multilayer light-emitting devices. NRF (Natl Research Foundation, S’pore) ASTAR (Agency for Sci., Tech. and Research, S’pore) Accepted version
Four-wave mixing in a ring cavity
2014
We investigate a four-wave mixing process in an N interaction scheme in Rb vapor placed inside a low-finesse ring cavity. We observe strong amplification and generation of a probe signal, circulating in the cavity, in the presence of two strong optical pump fields. We study the variations in probe field gain and dispersion as functions of experimental parameters with an eye on potential application of such a system for enhanced rotation measurements. A density-matrix calculation is performed to model the system, and the theoretical results are compared to those of the experiment.
Theory of parabolic pulse propagation in nonlinear dispersion decreasing optical fiber amplifiers
2008
Optical fibers ; Nonlinear optics ; Optical fiber amplifiers ; Optical amplifier ; Optical solitons ; Electromagnetic wave propagation ; Pulse propagation ;; International audience; We show that pulse spectral broadening in normally dispersive nonlinear fiber amplifiers may be enhanced by introducing a suitable dispersion tapering. We obtain an analytical dispersion profile that permits one to reduce pulse propagation in a varying dispersion fiber to the case of an equivalent fiber with constant parameters.
High frequency microwave signal generation using dual-wavelength emission of cascaded DFB fiber lasers with wavelength spacing tunability
2010
[EN] A dual wavelength fiber laser source based on two cascaded phase-shifted fiber Bragg gratings is presented The gratings are written in an erbium-doped fiber each configuring the cavity of a distributed feedback fiber laser The spacing between lasing modes is controlled dynamically by the use of piezoelectric actuators A continuous tuning range of 5-724 pm of the wavelength difference which is equivalent to a photodetected 072-92 GHz range is obtained Efficient generation from the L to the W microwave and millimeter bands has been achieved by heterodyne photodetection of the dual-wavelength optical signal (C) 2010 Elsevier BV All rights reserved
Hybrid magnetite–gold nanoparticles as bifunctional magnetic–plasmonic systems: three representative cases
2020
Hybrid systems based on magnetite and gold nanoparticles have been extensively used as bifunctional materials for bio- and nano-technology. The properties of these composites are assumed to be closely related to the magnetite to gold mass ratio and to the geometry of the resulting hetero-structures. To illustrate this, we compare and analyze the optical and magnetic properties of core-shell, dumbbell-like dimers and chemical cross-linked pairs of magnetite and gold nanoparticles in detail. We explore how the combination of gold with magnetite can lead to an improvement of the optical properties of these systems, such as tunability, light scattering enhancement or an increase of the local el…
Frequency tunable polarization and intermodal modulation instability in high birefringence holey fiber
2009
International audience; We present an experimental analysis of polarization and intermodal noise-seeded parametric amplification, in which dispersion is phase matched by group velocity mismatch between either polarization or spatial modes in birefringent holey fiber with elliptical core composed of a triple defect. By injecting quasi-CW intense linearly polarized pump pulses either parallel or at 45 degrees with respect to the fiber polarization axes, we observed the simultaneous generation of polarization or intermodal modulation instability sidebands. Furthermore, by shifting the pump wavelength from 532 to 625 nm, we observed a shift of polarization sidebands from 3 to 8 THz, whereas int…
Advanced ultra-high molecular weight polyethylene/antioxidant-functionalized carbon nanotubes nanocomposites with improved thermo-oxidative resistance
2015
Multiwalled carbon nanotubes (CNTs) functionalized with hindered phenol moieties are dispersed in ultra-high molecular weight polyethylene (UHMWPE), and the stabilizing action of the antioxidant (AO) functionalized CNTs (AO-f-CNTs) is studied through a combination of rheological and spectroscopic (FT-IR) analyses. The effectiveness of two alternative compounding methods, namely hot compaction (HC) and melt mixing (MM), is compared. The combination of high temperature and mechanical stress experienced during MM brings about noticeable degradation phenomena of the matrix already in the course of the compounding step. Differently, the milder conditions of the HC process preserve the stability …