Search results for " parametri"

PARAMETRIC SELF-TRAPPING OF OPTICAL BEAMS VIA RANDOM QUASI PHASE MATCHING IN LITHIUM TANTALATE WAVEGUIDE

2011

We report on experimental evidence of parametric spatial solitons in a lithium tantalate waveguide with randomized periodic ferroelectric poling. Two-color self-focusing via quadratic cascading overcomes the diffractive nature of both fundamental and frequency-doubled beams.

Parametric frequency conversion of optical simulton pulses

2007

We present an analytical description of the parametric frequency conversion of short solitary wave optical pulses in quadratic nonlinear crystals controlled by means of a continuous wave background.

Emergence of extreme events in fiber-based parametric processes driven by a partially incoherent pump wave

2009

Modulation instability (MI) generated by a picosecond coherent pulse has been recently identified as the key element of the generation of optical rogue-waves in supercontinuum-based systems [1]. Similar rare but highly energetic pulse structures can also appear in non-solitonic configurations such as Raman amplifiers driven by a partially incoherent pump wave propagating in fibres with low group velocity dispersion [2]. Therefore, one may wonder whether optical rogue-like event can also occur in MI-based amplifier because both Raman and parametric amplifiers benefit from a quasi-instantaneous gain. We provide here experimental evidence of rare optical events in a parametric amplifier in pre…

Record Phase Sensitive Extinction Ratio in a Silicon Germanium Waveguide

2015

A binary step-like phase response and phase-sensitive extinction ratio in excess of 28dB under CW pump operation was demonstrated in a 20mm-long low birefringence SiGe waveguide, using a polarization-assisted phase sensitive amplifier scheme.

Demonstration of polarization pulling using a fiber-optic parametric amplifier

2012

International audience; We report the observation of all-optical polarization pulling of an initially polarization-scrambled signal using parametric amplification in a highly nonlinear optical fiber. Broadband polarization pulling has been achieved both for the signal and idler waves with up to 25 dB gain using the strong polarization sensitivity of parametric amplifiers. We further derive the probability distribution function for the final polarization state, assuming a randomly polarized initial state, and we show that it agrees well with the experiments.

Nonlinear Resonance Effects in Pattern Formation in Optical Parametric Oscillators

2005

Kontrolētas dedzināšanas ietekme uz augsnes bruņērču (Acari:Oribatida) sugu sabiedrībām priežu mētrājā, aizsargājamo ainavu apvidū "Ādaži"

2018

Bruņērces līdz šim ir maz izmantotas sukcesiju pētījumos un zināšanas par augsnes faunas un bruņērču atbildes reakcijām uz dažādiem traucējumiem ir ierobežotas, taču to relatīvi lēnais dzīves cikls un plašā izplatība tās padara par efektīviem ilgtermiņa bioindikatoriem, kas var liecināt par degšanas ietekmes smagumu. Darba mērķis ir noskaidrot kontrolētas dedzināšanas ietekmi uz augsnes bruņērču sabiedrībām, zemsedzi un augsnes parametriem priežu mētrājā. Augsnes paraugi ievākti pirms un 16 dienas pēc kontrolētas dedzināšanas. Pēc degšanas bruņērču indivīdu skaits samazinājies par 93% un sugu skaits par 77%. Izmaiņas ietekmē degšanas ietekmes smagums. Pēc traucējuma eudominējošs taksons ir …

Information systems for the conservation and fruition of cultura heritage. The church of Santa Trinità di Delia

2016

Lo studio descrive il processo di conoscenza avviato su uno degli esempi monumentali più rappresentativi dell’architettura normanna della prima metà del XII sec. in Sicilia: la chiesa della Trinità di Delia a Castelvetrano (TP). Le fasi del rilievo e della rappresentazione 3D degli elementi costruttivi e decorativi seguono un approccio parametrico costituendo un sistema informativo implementabile di supporto per successivi interventi di restauro conservativo della struttura. Il workflow è struturato in modo tale da impiegare tecnologie hardware / software low-cost, descrivendo metodiche procedurali di elaborazione dati trasferibili all’attività professionale. The study describes the knowled…

Synchronization of optical photons for quantum information processing

2015

We observe the Hong-Ou-Mandel interference via homodyne tomography on two photons extracted from two quantum memories.

Comprehensive formulation of the temperature dependent dispersion of optical materials; illustration with the case of temperature tuning of a mid-IR …

2009

International audience; The temperature dependence of refractive indices of optical materials is characterized in this work by what we call their normalized thermo-optic coefficients. These ones are determined experimentally through interferometric measurements of thermal expansion, and changes in optical thickness at a few laser wavelengths as function of temperature. A suitable vectorial formalism applied to these data allows predicting the thermal evolution of the refractive index all over the useful range of transparency. The validity and reliability of our methodology is demonstrated through temperature tuning of a mid-IR HgGa2S4 OPO, pumped at 1.0642 μm by a Nd:YAG laser. Measured the…