Search results for "Kerr"
showing 10 items of 494 documents
Rajan tiloja : luonnollisuus, luonnottomuus ja epäluonnottomuus 2000-luvun pohjoismaisissa autofiktioissa
2015
Epäkerrottu ja vastakerronta Ben Lernerin romaanissa 10:04
2017
Tutkielman tavoitteena on analysoida henkilökertojan sisäisen maailman esittämistä yhdysvaltalaisen Ben Lernerin romaanissa 10:04 (2014) Gerald Princen epäkerrotun (engl. disnarrated) ja Brian Richardsonin vastakerronnan (engl. denarration) käsitteiden pohjalta. Narratologiassa epäkerrotun käsitteellä tarkoitetaan sellaisia kerrottuja tapahtumia, jotka eivät toteudu kertomuksen tarinamaailmassa, mutta ovat siellä kuitenkin mahdollisia. Vastakerronnalla viitataan puolestaan kerronnan tilanteisiin, joissa kiistetään tai perutaan kertomuksen elementtejä, jotka on siihen asti esitetty tarinamaailmaan kuuluvina. Tässä tutkielmassa epäkerrottua ja vastakerrontaa käsitellään erityisesti henkilöker…
Determination of third-order nonlinear optical properties of ABI derivatives
2019
This material is based upon work supported by the ERDF 1.1.1.1 activity project Nr. 1.1.1.1/16/A/046 “Application assessment of novel organic materials by prototyping of photonic devices”.
Determination of Kerr and two-photon absorption coefficients of ABI thin films
2018
This material is based upon work supported by the ERDF 1.1.1.1 activity project Nr. 1.1.1.1/16/A/046 “Application assessment of novel organic materials by prototyping of photonic devices”
Vertical stratification patterns of methanotrophs and their genetic controllers in water columns of oxygen-stratified boreal lakes
2021
ABSTRACT The vertical structuring of methanotrophic communities and its genetic controllers remain understudied in the water columns of oxygen-stratified lakes. Therefore, we used 16S rRNA gene sequencing to study the vertical stratification patterns of methanotrophs in two boreal lakes, Lake Kuivajärvi and Lake Lovojärvi. Furthermore, metagenomic analyses were performed to assess the genomic characteristics of methanotrophs in Lovojärvi and the previously studied Lake Alinen Mustajärvi. The methanotroph communities were vertically structured along the oxygen gradient. Alphaproteobacterial methanotrophs preferred oxic water layers, while Methylococcales methanotrophs, consisting of putative…
Spatial beam self-cleaning in multimode fibres
2017
Multimode optical fibres are enjoying a renewed attention, boosted by the urgent need to overcome the current capacity crunch of single-mode fibre systems and by recent advances in multimode complex nonlinear optics [1-13]. In this work, we demonstrate that standard multimode fibres can be used as ultrafast all-optical tool for transverse beam manipulation of high power laser pulses. Our experimental data show that the Kerr effect in a graded-index multimode fibre is the driving mechanism for overcoming speckle distortions, leading to a somewhat counter-intuitive effect resulting in a spatially clean output beam robust against fibre bending. Our observations demonstrate that nonlinear beam …
Electrostrictive cross-phase modulation of periodic pulse trains in optical fibers
1998
Electrostriction-induced cross-phase modulation between subsequent bits of a nonreturn-to-zero pulse train in optical fibers leads to nonlinear frequency shifts of opposite sign for the 1’s and the 0’s. Direct experimental measurements of the electrostrictive and Kerr-induced nonlinear phase shift across the bit profiles agree well with the theoretical modeling.
Highly efficient few-mode spatial beam self-cleaning at 15µm
2020
We experimentally demonstrate that spatial beam self-cleaning can be highly efficient when obtained with a few-mode excitation in graded-index multimode optical fibers. By using 160 ps long, highly chirped (6 nm bandwidth at -3dB) optical pulses at 1562 nm, we demonstrate a one-decade reduction of the power threshold for spatial beam self-cleaning, with respect to previous experiments using pulses with laser wavelengths at 1030-1064 nm. Self-cleaned beams remain spatio-temporally stable for more than a decade of their peak power variation. The impact of input pulse temporal duration is also studied.
Non-Linear Optical Properties of Hybridized Surface Plasmon Polaritonic Crystals: Observation of Optical Bistability
2007
Summary form only given. The use of surface plasmons (SP) is recognized as being central to the development of nanoscale assemblies of photonic and opto-electronic devices. This is motivated by the spatially confined nature of these electromagnetic waves as well as their resonant behavior. Amongst plasmonic supporting structures, surface plasmonic crystals (SPCs) draw particular interest because of their tailored optical properties. A geometry common to SPCs consists in a periodic arrangement of holes or slits in a metal film. Their complex optical response is then governed by coherent interactions between Bloch modes at the film's interfaces and modes supported by the holes or slits. These…
CARACTÉRISATION ET MODÉLISATION DE PEIGNES DE FRÉQUENCES KERR DANS DES CAVITÉS LASER BRILLOUIN À FIBRE
2022
Nous étudions une cavité en anneau non réciproque simple et reconfigurable pour générer des peignes de fréquences optiques accordables. Nous démontrons que des peignes cohérents peuvent être obtenus en exploitant finement la rétrodiffusion Brillouin stimulée et le mélange à quatre ondes en cascade dans la cavité à fibre non-linéaire.