Search results for "harmonic generation"

Novel second-order nonlinear optical polymer materials containing indandione derivativatives as a chromophore

2006

Second order non linear optical (NLO) properties of sPMMA based host-guest systems containing eight dimethylaminobenzylidene -1, 3 - indandione (DMABI) related chromophores have been investigated by means of quantum chemical calculations and SHG experimental characterization. Ab initio calculations with basis set 6-31G were used for molecular geometry determination as well as in the calculations of molecular hyperpolarizability by FF approach. Influence of the chromophore concentration on the host-guest film NLO performance was obtained by SHG Maker fringe experiments. The highest value of d53233 =80 pm/V (frequency corrected value d033 =12 pm/V) at chromophore concentration 15 %wt have bee…

Second harmonic generation and beam cleaning in optically poled multimode graded-index fibers

2017

Recent experimental results have confirmed that nonlinear effects in multimode graded-index (MM-GRIN) fibers lead to a wealth of observable spatiotemporal effects. In spite of the large number of modes supported by the fiber, by increasing the input power the transverse profile evolves in a clean bell-shaped beam [1, 2]. Next, the input laser line experiences a strong spectral broadening and Geometric Parametric Instability (GPl) peaks are observed [3].

Spatial beam cleaning in quadratic nonlinear medium

2018

We show experimentally that a laser beam scrambled by propagation in a short segment of multimode fiber may be cleaned by the nonlinear propagation in KTP cristal with type-II second-harmonic generation.

Second- and third-harmonic generation as a local probe for nanocrystal-doped polymer materials with a suppressed optical breakdown threshold

2003

Abstract Second- and third-harmonic generation processes are shown to allow the detection of absorptive agglomerates of nanocrystals in transparent materials and the visualization of optical breakdown in nanocomposite materials. Correlations between laser-induced breakdown and the behavior of the second- and third-harmonic signals produced in SiC/PMMA nanocomposite films are studied. The potential of second- and third-harmonic generation for the on-line visualization of laser breakdown in nanocomposite polymer materials is revealed, with the ablative material removal being monitored by the decay of the second- and third-harmonic signals. The second and third harmonics generated around the o…

Nanorings driven by strong laser fields: dynamics and applications

Optical characterization of YCa4O(BO3)3 and Nd:YCa4O(BO3)3 crystals

2007

International audience; We report a complete optical characterization of YCa4O(BO3)3 and Nd:YCa4O(BO3)3 crystals. We studied the relative orientation between the dielectric and the crystallographic frames as a function of the wavelength and performed accurate phase-matching angles measurements for second harmonic generation, using a single crystal cut as a sphere. We also recorded polarized luminescence spectra of Nd:YCOB along the principal axes of the dielectric frame. For both crystals, we measured the gray-tracking and the thermo-optic properties as a function of temperature and wavelength using oriented slabs. Finally, we measured all their dielectric and electro-optic coefficients, as…

Nanopatterned ferroelectric crystals for parametric generation

2006

We report on recent results by surface periodic poling on lithium niobate and lithium tantalate. Such approach allows periodic inversion of the second order susceptibility with nanoscale features using insulating masks. We achieved a world-best 200 nm feature size, as well as good compatibility with alpha-phase proton exchanged channel waveguides in lithium niobate. Preliminary results of surface periodic poling in lithium tantalate also show similar characteristics. Surface poling is best suited for integrated optics devices in technologically-demanding configurations such as backward second harmonic generation and counter propagating optical parametric amplification

Nonlinear Microwave Spectrometer for Investigating High-Tc Superconductors

2000

We describe a nonlinear microwave spectrometer, which can be conveniently used for investigating the harmonic generation at microwave frequencies in high-Tc superconductors. The use of this technique allows highlighting mechanisms responsible for the nonlinear microwave response of high-Tc superconductors as well as measuring specific characteristics of the investigated samples. We report a brief review of the main results obtained.

GENERAZIONE DI SECONDA ARMONICA RETRO-PROPAGANTE IN NIOBATO DI LITIO CON POLING PERIODICO

2010

We report on backward second-harmonic-generation in bulk periodically poled congruent lithium niobate with a 3.2 micron period. A tunable continuous-wave Ti:Sapphire laser allowed us exciting two resonant quasi-phase-matched orders. Resonances were also resolved by temperature tuning.

Guided-wave frequency doubling in surface periodically poled lithium niobate: competing effects

2007

We carried out second-harmonic generation in quasi-phase-matched ? -phase lithium niobate channel waveguides realized by proton exchange and surface periodic poling. Owing to a limited ferroelectric domain depth, we could observe the interplay between second-harmonic generation and self-phase modulation due to cascading and cubic effects, resulting in a nonlinear resonance shift. Data reduction allowed us to evaluate both the quadratic nonlinearity in the near infrared as well as the depth of the uninverted domains. © 2007 Optical