Modeling of quasi-phase-matched cavity enhanced second harmonic generation

We propose a mean-field model to describe second harmonic generation in a resonator made of a material with zincblende crystalline structure. The model is obtained through an averaging of the propagation equations and boundary conditions. It considers the phase-mismatched terms, which act as an effective Kerr effect. We analyze the impact of the different terms on the steady state solutions, highlighting the competition between nonlinearities

Measurement of the third order optical nonlinearities of graphene quantum dots in water at 355 nm, 532 nm and 1064 nm

The nonlinear responses of the suspension of graphene quantum dots (GQDs) in water are investigated at 355 nm, 532 nm and 1064 nm in the picosecond regime. The third-order nonlinear (NL) refractive index and the NL absorption coefficients are determined. We found that only under UV illumination is the NL response large. Furthermore, the NL refractive index and the saturable absorption are estimated for a single nanoparticle constituting the GQDs through a simple model. The obtained value of the Kerr coefficient is in the order of magnitude of that found in bulk materials and three orders of magnitude lower with an opposite sign than that found for the monolayer graphene

Dark field Z-scan microscopic configuration for nonlinear optical measurements: Numerical study

This study deals with numerical simulations to optimize the parameters of the Dark Filed Z-scan (DFZ-scan) in a microscopic configuration for third-order nonlinear (NL) refraction measurements into thin films. The method allows dynamic, transparent, nonlinear phase shifts to be clearly visible. The simulations of such images are obtained for very low-induced refractive indices. Darkfield illumination requires blocking out of the central light which ordinarily passes through and around (surrounding) the NL specimen. A table to approximate circular aperture stop size versus magnification will be given depending on the focusing lens into the tested material

Optical nonlinear propagation dynamics in silicon photonic wire waveguides

info:eu-repo/semantics/publishe

Measuring the nonlinear refractive index of graphene using the optical Kerr effect method

© 2016 Optical Society of America.By means of the ultrafast optical Kerr effect method coupled to optical heterodyne detection (OHD-OKE), we characterize the third-order nonlinear response of graphene and compare it to experimental values obtained by the Z-scan method on the same samples. From these measurements, we estimate a negative nonlinear refractive index for monolayer graphene, n2 = -1.1 × 10-13 m2/W. This is in contradiction to previously reported values, which leads us to compare our experimental measurements obtained by the OHD-OKE and the Z-scan method with theoretical and experimental values found in the literature and to discuss the discrepancies, taking into account parameters such as doping

Asiatic clam Corbicula fluminea exhibits distinguishable behavioural responses to crude oil under semi-natural multiple stress conditions

International audienc

Proteome changes in muscles, ganglia, and gills in Corbicula fluminea clams exposed to crude oil: Relationship with behavioural disturbances

International audienc

Reflection from a free carrier front via an intraband indirect photonic transition

The reflection of light from moving boundaries is of interest both fundamentally and for applications in frequency conversion, but typically requires high pump power. By using a dispersion-engineered silicon photonic crystal waveguide, we are able to achieve a propagating free carrier front with only a moderate on-chip peak power of 6 W in a 6 ps-long pump pulse. We employ an intraband indirect photonic transition of a co-propagating probe, whereby the probe practically escapes from the front in the forward direction. This forward reflection has up to 35% efficiency and it is accompanied by a strong frequency upshift, which significantly exceeds that expected from the refractive index change and which is a function of group velocity, waveguide dispersion and pump power. Pump, probe and shifted probe all are around 1.5 μm wavelength which opens new possibilities for "on-chip" frequency manipulation and all-optical switching in optical telecommunications