NERADOVSKIY , Maxim

The investigation of influence of the soft proton exchange (SPE) optical waveguide (WG) creation onperiodically poled lithium niobate (PPLN) has been done. It has been shown that the WG fabricationprocess can induce the formation of needle like nanodomains, which can be responsible for thedegradation of the nonlinear response of the WG created...

Twisted cholesteric liquid crystal patterns are found in the iridescent chitin-containing cuticles of many insects. They may exhibit spatial variation in the helical pitch and in the orientation of the helix axis, as in the two-band, green and silver cuticle of the scarab beetle, Chrysina gloriosa, which is the focus of the present study. The...

Biological systems inspire the design of multifunctional materials and devices. However, current synthetic replicas rarely capture the range of structural complexity observed in natural materials. Prior to the definition of a biomimetic design, a dual investigation with a common set of criteria for comparing the biological material and the...

International audience

International audience

We demonstrate the ability to manipulate ultrashort pulses in cholesteric liquid crystals in the linear regime. We present an extensive analysis of the spectral changes undergone by 20fs pulses when propagating through band edges of cholesteric liquid crystals. The accurate quantification of the introduced optical dispersion opens the way to...

Imperfections of the periodic material impact the performances of Quasi Phase Matched devices. Our numerical study allows predicting the impact of stitching errors on the nonlinear interactions in waveguides using domains induced by e-beam writing in Lithium Niobate and explaining the observed experimental results.

We propose an advanced optical characterization of CLC samples, using ultrashort pulses and a statistical approach to experimentally quantify the temporal changes undergone when a femtosecond pulse propagates in the linear regime through the edges of the photonic bandgap.

National audience

The domain structure evolution has been studied in congruent lithium niobate crystals with surface layers modified by three different proton exchange techniques. The significant decrease of the nucleation threshold field and qualitative change of domain rays nucleation and growth have been revealed. The formation of a broad domain boundary and...

In this paper, we present the material characterization that has been made to explain the poor nonlinear performance observed in certain channel waveguides produced by soft proton exchange in periodically poled congruent lithium niobate (PPLN) crystals. The study was performed using complementary methods of domain visualization: piezoelectric...

International audience

Depending on the chosen fabrication process, nonlinear waveguides realized in periodically oriented material such as PPLN can present different fabrication errors. In this paper we present a detailed numerical study of the impact on the nonlinear performances of one or several stitching errors occurring during the realization of the periodic...

In integrated photonics, the precise knowledge of the waveguides refractive index profile is mandatory for the modeling of photonic chips and therefore implementing innovative circuits. Usual index profile determination relies on effective index measurement of propagating modes in planar waveguides coupled with numerical fitting tools. In this...

The strong dependence of the domain kinetics on the applied field and the thickness of the surface layers produced by proton exchange has been revealed in congruent lithium niobate. The correlated nucleation leads to formation of self-assembled structures consisting of isolated domains. Formation of the nanodomains in front of the domain wall...

International audience

Dans cette étude, pour nous assurer que la fabrication des guides n'induise aucun effet parasites comme la création de nanodomaines, la réductions du coefficient non linéaire ou le coupage des polarisations ordinaires et extra-ordinaire induit par les contraintes mécaniques, nous avons utilisé des guides à gradient d'indice présentant une très...

Formation of domain structure by electron beam irradiation in congruent lithium niobate covered by surface dielectric layer with planar and channel waveguides produced by Soft Proton Exchange (SPE) process has been studied. Formation of domains with arbitrary shapes as a result of discrete switching has been revealed. The fact was attributed to...

International audience

International audience