Search results for "second-harmonic generation"

Second harmonic generation in ferroelectric liquid crystalline thiadiazole derivatives

1995

Diffractive optics for spectral tuning of second harmonic and supercontinuum generated in nonlinear crystals

2011

It is shown that diffractive lenses can tune the spectrum of femtosecond pulses after nonlinear optical processes. We focus on spectra of second-order pulses generated in birefringent crystals and supercontinuum in sapphire crystals. The tunability is achieved by changing the relative distance between the nonlinear crystal and the diffractive lens.

Dispersion Compensation in Holograms Reconstructed by Femtosecond Light Pulses

2014

This chapter describes how the spatiotemporal dispersion associated with the diffraction of broadband femtosecond light pulses through computer generated holograms (CGHs) can be compensated to a first order with a properly designed dispersion compensation module (DCM). The angular dispersion of the beam associated to CGHs leads to both spatial and temporal distortion of the pulse. Some experiments in one-shot second harmonic generation, wide-field two-photon microscopy, and parallel micromachining are shown to study the quality of the compensation performed with the DCM.

Silencing and enhancement of second-harmonic generation in optical gap antennas

2012

International audience; Amplifying local electromagnetic fields by engineering optical interactions between individual constituents of an optical antenna is considered fundamental for efficient nonlinear wavelength conversion in nanometer-scale devices. In contrast to this general statement we show that high field enhancement does not necessarily lead to an optimized nonlinear activity. In particular, we demonstrate that second-harmonic responses generated at strongly interacting optical gap antennas can be significantly suppressed. Numerical simulations are confirming silencing of second-harmonic in these coupled systems despite the existence of local field amplification. We then propose a…

Directional Second Harmonic Generation Controlled by Sub-wavelength Facets of an Organic Mesowire

2018

Directional harmonic generation is an important property characterizing the ability of nonlinear optical antennas to diffuse the signal in well-defined region of space. Herein, we show how sub-wavelength facets of an organic molecular mesowire crystal can be utilized to systematically vary the directionality of second harmonic generation (SHG) in the forward scattering geometry. We demonstrate this capability on crystalline diamonoanthraquinone (DAAQ) mesowires with subwavelength facets. We observed that the radial angles of the SHG emission can be tuned over a range of 130 degrees. This angular variation arises due to spatially distributed nonlinear dipoles in the focal volume of the excit…

High efficiency frequency doubling in fully diced LiNbO3ridge waveguides on silicon

2016

Nonlinear periodically poled ridge LiNbO3 waveguides have been fabricated on silicon substrates. Components are carved with only the use of a precision dicing machine without the need for grinding or polishing steps. They show efficient second harmonic generation at telecommunication wavelengths with normalized conversion reaching 204%/W in a 15 mm long device. The influence of the geometrical non uniformities of waveguides due to fabrication processes is asserted. Characteristics of the components are studied; notably their robustness and tunability versus temperature.

Towards CEP stable, single-cycle 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 1.6 cycles at 1.8 µm wavelength.

Experimental properties of parabolic pulses generated via Raman amplification in standard optical fibers

2004

Parabolic pulses at 1550 nm have been generated in a standard telecommunications fiber using Raman amplification. The parabolic output pulse characteristics are studied as a function of input pulse energy and duration.

Langmuir-Blodgett films of indandione-1,3 pyridinium betaine. III: Linear dichroism and non-linear optical properties

1996

Linear dichroism and second-harmonic generation (SHG) have been measured in Langmuir-Blodgett (LB) multilayers of Z-type structure of amphiphilic indandione-1,3 pyridinium betaine (IPB) with an aliphatic tail containing 17 carbon atoms (C171PB). The dichr

Harmonic emission at microwave frequencies in Ba0.6K0.4BiO3 crystals

1998

Abstract Nonlinear microwave emission by Ba0.6K0.4BiO3 crystals is investigated. Second- and third-harmonic signals are studied as a function of the temperature and the applied magnetic field at different values of the input power level. The experimental data are discussed in the framework of models previously reported in the literature. We show that there are several mechanisms responsible for harmonic emission in Ba0.6K0.4BiO3 crystals: they play a different role depending on the temperature and the intensity of the applied field. We suggest that harmonic emission at temperatures far from Tc is due to nonlinear processes in weak links or flux motion, while nonlinearity near Tc is ascribab…