Search results for "second-harmonic"
showing 10 items of 121 documents
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…
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
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
Towards CEP stable sub two cycle IR pulse compression with bulk material
2010
We demonstrate both experimentally and numerically that self-steepening during propagation in a hollow-fiber followed by linear propagation through glass in the anomalous dispersion enables pulse compression down to 1.9 cycles at 1.8 micron wavelength.
Backward frequency doubling of near infrared picosecond pulses.
2014
We report on backward second-harmonic generation using ps laser pulses in congruent lithium niobate with 3.2 µm periodic poling. Three resonant peaks were measured between 1530 and 1730 nm, corresponding to 16th, 17th and 18th quasi-phase-matching orders in the backward configuration, with a conversion efficiency of 4.75 x 10(-5%)/W for the 16th order. We could also discriminate the contributions from inverted domains randomized in duty-cycle.
Grating-assisted third-harmonic generation in photonic crystal fibers using a pulse pump
2011
We demonstrate that quasi-phase-matching of the third-harmonic generation process can be obtained for a pulse pump in the photonic crystal fiber with a refractive-index grating. Conversion efficiency is calculated numerically using a system of coupled generalized nonlinear Schrodinger equations. We propose a special design of the microstructured fiber for the third-harmonic generation and analyze different phenomena limiting the maximum efficiency for short (femtosecond) and long (picosecond) pump pulses. Moreover, we show that a certain level of a group-velocity mismatch between the pump and the third harmonic can increase the maximum efficiency in the long pulse regime.
Soft proton exchanged channel waveguides in congruent lithium tantalate for frequency doubling
2010
We report on stable optical waveguides fabricated by soft-proton exchange in periodically-poled congruent lithium tantalate in the a-phase. The channel waveguides are characterized in the telecom wavelength range in terms of both linear properties and frequency doubling. The measurements yield a nonlinear coefficient of about 9.5pm/V, demonstrating that the nonlinear optical properties of lithium tantalate are left nearly unaltered by the process. (C) 2010 Optical Society of America
Triple excitation effects in coupled-cluster calculations of frequency-dependent hyperpolarizabilities
1998
Abstract We describe an implementation of an analytic scheme for the calculation of static and dynamical first hyperpolarizabilities at the CC3 level in the framework of coupled-cluster response theory. Calculations are reported for the static, the second harmonic generation, and the optical rectification hyperpolarizabilities of FH. The results indicate the importance of triple excitation effects for accurate theoretical predictions of hyperpolarizabilities and lend further support to previous contentions that an experimental value for the second harmonic generation hyperpolarizabilities of FH should be reconsidered.