Search results for "UAS"
showing 10 items of 1619 documents
Quasi-local quasi -algebras of measurable operators
2011
In this paper we will continue the analysis undertaken in [1] and in [2] our investigation on the structure of Quasi-local quasi *-algebras. In this paper it is shown that any Quasi-local quasi -algebras (A;A_0), can be represented as a class of Banach C-modules called CQ-algebra of measurable operators in Segal's sense.
On Commuting Quasi-Nilpotent Operators that are Injective
2022
Banach space operators that commute with an injective quasi-nilpotent operator, 11 such as the Volterra operator, inherit spectral and Fredholm properties, relating in 12 particular to the Weyl spectra.
Parametric self-trapping in the presence of randomized quasi phase matching
2010
We report on experimental evidence of parametric spatial solitons in a quadratic crystal with randomized periodic ferroelectric poling. Two-color self-focusing via quadratic cascading overcomes the diffractive nature of both fundamental and frequency-doubled beams.
Ultraviolet quasi-phase-matched second harmonic generation in surface periodically poled lithium niobate optical waveguides
2007
The compatibility of low concentration (alpha-phase) proton exchange channel waveguides with electric field surface periodic poling of congruent lithium niobate (SPPLN) crystals has been experimentally demonstrated. With such waveguides, we obtained ultraviolet second harmonic generation (SHG) by first order quasi-phase-matching (QPM), a result made possible by the fabrication, on Z-cut LN crystals, of periodic structures with a pitch down to 750 nm. Nonlinear copropagating QPM-SHG measurements have been carried out on such structures. The pump source was a Ti:sapphire laser with a tunability range of 700-980 nm and a 40 GHz linewidth. We have measured UV continuous wave light at 390 nm by …
Integrated frequency shifter in periodically poled lithium tantalate waveguide
2010
A frequency shifting device is fabricated and tested in a ferroelectric waveguide in a low-photorefractivity crystal. Periodic poling for quasi-phase-matching and channels for operation in the near-infrared C-band were obtained in congruent lithium tantalate, demonstrating for the first time both wave confinement and two-stage parametric conversion in such waveguides.
Dynamics of four-wave-mixing oscillators with quasi-phase-matching
2009
The effect of pump-wave misalignment on the oscillation spectra of a semilinear photorefractive oscillator is studied numerically and compared with the results of experiments performed with ${\text{BaTiO}}_{3}:\text{Co}$ and ${\text{KNbO}}_{3}:\text{Ag},\text{Fe}$ crystals.
Random quasi-phase matching in congruent lithium tantalate waveguides by proton exchange
2012
A report is presented on broadband second-harmonic generation in the range between 930 and 970 nm using random quasi-phase matching in a planar waveguide fabricated by soft proton exchange in congruent lithium tantalate. Bulk and waveguide measurements are compared, outlining the averaging role of guided-wave modes and their interactions with respect to spectral acceptance and near-field profile.
Planar Mappings of Finite Distortion
2010
We review recent results on planar mappings of finite distortion. This class of mappings contains all analytic functions and quasiconformal mappings.
A quasiconformal composition problem for the Q-spaces
2017
Given a quasiconformal mapping $f:\mathbb R^n\to\mathbb R^n$ with $n\ge2$, we show that (un-)boundedness of the composition operator ${\bf C}_f$ on the spaces $Q_{\alpha}(\mathbb R^n)$ depends on the index $\alpha$ and the degeneracy set of the Jacobian $J_f$. We establish sharp results in terms of the index $\alpha$ and the local/global self-similar Minkowski dimension of the degeneracy set of $J_f$. This gives a solution to [Problem 8.4, 3] and also reveals a completely new phenomenon, which is totally different from the known results for Sobolev, BMO, Triebel-Lizorkin and Besov spaces. Consequently, Tukia-V\"ais\"al\"a's quasiconformal extension $f:\mathbb R^n\to\mathbb R^n$ of an arbitr…