Search results for "Linear system"
showing 10 items of 1558 documents
Nonlinear frequency conversion in a birefringent microstructured fiber tuned by externally applied hydrostatic pressure.
2013
We studied vector frequency conversion in externally tuned microstructured fibers for applications as a novel, nonlinear fiber-optic sensor. We investigated both experimentally and numerically a possibility of shifting vector and scalar modulation instability gain bands by pressure-induced changes in the linear properties of a microstructured fiber. Our results show that polarization-dependent vector nonlinear processes sensitive to variation of fiber group velocity difference (group birefringence) exhibit a clear advantage for pressure-sensing applications compared with scalar nonlinear processes only sensitive to group velocity dispersion changes. Analytical predictions and numerical simu…
Temperature dependence of refractive index and absorption coefficient of GaSe at 633 nm
1995
Abstract Measurements of the ordinary refractive index and the absorption coefficient ( E /t] to c axis ) of gallium selenide at 633 nm, in the temperature range [20,100] °C, are reported. Useful analytical approximations obtained after a least squares fitting process are provided, as well. These results are basic for any theoretical model of nonlinear and bistable optical devices based on GaSe.
Applicability Range of the One-Parameter Ply Plasticity Model for Prediction of the Nonlinear Response of Laminates
2005
A one-parameter lamina plasticity model is applied to predict the nonlinear deformation of an E-glass / epoxy cross-ply composite laminate under quasi-static uniaxial tensile loading at different angles to the material orthotropy axes. It is shown that the laminate theory yields accurate results within the plastic strain range covered in unidirectional continuous-fibre reinforced composite tests that are used to determine the plasticity model parameters.
Pressure-induced band anticrossing in two adamantine ordered-vacancy compounds: CdGa2S4 and HgGa2S4
2021
Abstract This paper reports a joint experimental and theoretical study of the electronic band structure of two ordered-vacancy compounds with defect-chalcopyrite structure: CdGa2S4 and HgGa2S4. High-pressure optical-absorption experiments (up to around 17 GPa) combined with first-principles electronic band-structure calculations provide compelling evidence of strong nonlinear pressure dependence of the bandgap in both compounds. The nonlinear pressure dependence is well accounted for by the band anticrossing model that was previously established mostly for selenides with defect chalcopyrite structure. Therefore, our results on two sulfides with defect chalcopyrite structure under compressio…
Nonlinear Disorder Mapping via Wave Mixing in poled Lithium Tantalate
2010
We introduce and test a simple approach for the characterization of domain distribution in bulk quadratic ferroelectric crystals, specifically periodically poled Lithium Tantalate with random mark-to space ratio.
Nonlinear Disorder Mapping via Three Wave Mixing in Poled Lithium Tantalate
2010
We introduce and test a simple approach for the characterization of domain distribution in bulk quadratic ferroelectric crystals, such as periodically poled Lithium Tantalate with random mark-to space ratio.
Modeling non-linear dielectric susceptibilities of supercooled molecular liquids
2021
Advances in high-precision dielectric spectroscopy have enabled access to non-linear susceptibilities of polar molecular liquids. The observed non-monotonic behavior has been claimed to provide strong support for theories of dynamic arrest based on the thermodynamic amorphous order. Here, we approach this question from the perspective of dynamic facilitation, an alternative view focusing on emergent kinetic constraints underlying the dynamic arrest of a liquid approaching its glass transition. We derive explicit expressions for the frequency-dependent higher-order dielectric susceptibilities exhibiting a non-monotonic shape, the height of which increases as temperature is lowered. We demons…
Tunable coaxial cavity resonator for linear and nonlinear microwave characterization of superconducting wires
2011
We discuss experimental results obtained using a tunable cylindrical coaxial cavity constituted by an outer Cu cylinder and an inner Pb-BSCCO wire. We have used this device for investigating the microwave response of the superconducting wire, both in the linear and nonlinear regimes. In particular, by tuning the different modes of the cavity to make them resonant at exactly harmonic frequencies, we have detected the power emitted by the superconducting inner wire at the second- and third-harmonic frequency of the driving field. The results obtained in the nonlinear regime, whether for the microwave surface impedance or the harmonic emission, are qualitatively accounted for considering inter…
Three-Dimensional Printing of Nonlinear Optical Lenses.
2018
In the current paper, a series of nonlinear optical (NLO) active devices was prepared by utilizing stereolithographic three-dimensional printing technique. Microcrystalline NLO active component, urea, or potassium dihydrogen phosphate was dispersed in a simple photopolymerizable polyacrylate-based resin and used as the printing material to fabricate highly efficient transparent NLO lenses. The nonlinear activity of the printed lenses was confirmed by second-harmonic generation measurements using a femtosecond laser-pumped optical parametric amplifier operating at a wavelength of 1195 nm. The three-dimensional printing provides a simple method to utilize a range of NLO active compounds witho…
Harmonic emission at microwave frequencies in YBa2Cu3O7 single crystals near Tc
1998
Abstract Nonlinear microwave emission by YBa 2 Cu 3 O 7 single crystals is investigated at temperatures close to T c . Second- and third-harmonic signals are studied as a function of the temperature and input power, for different values of the external magnetic field. The results are discussed in the framework of a phenomenological theory based on the two-fluid model which assumes that both the microwave and static fields perturb the partial concentrations of the normal and condensate fluids. It is suggested that, at temperatures very close to T c , this mechanism is the only one responsible for the harmonic emission by YBa 2 Cu 3 O 7 single crystals in the Meissner state. It is also effect…