Search results for "Modula"

Instabilities of four-wave mixing

2005

We predict that four-wave mixing driven by a dual frequency input undergoes different instability scenarios encompassing modulational instability or multiple shock formation in the anomalous and normal dispersion regime, respectively.

Arresting soliton collapse in two-dimensional nonlinear Schrödinger systems via spatiotemporal modulation of the external potential

2007

We predict stable, collapse-free solitonslike structures in two-dimensional nonlinear Schr\"odinger systems in subdiffractive regimes, accomplished by a spatiotemporal modulation of the external potential. We investigate the scaling laws, the stability, and the dynamical properties of these subdiffractive solitons.

Suppression of soliton self-frequency shift by up-shifted filtering

2002

We propose an efficient method for suppressing the soliton self-frequency shift in high-speed transmission lines by means of up-shifted filters.

The on-board calibration system of the X-ray Imaging Polarimetry Explorer (XIPE)

2016

The calibration system for XIPE is aimed at providing a way to check and correct possible variations of performance of the Gas Pixel Detector during the three years of operation in orbit (plus two years of possible extended operation), while facilitating the observation of the celestial sources. This will be performed by using a filter wheel with a large heritage having a set of positions for the calibration and the observation systems. In particular, it will allow for correcting possible gain variation, for measuring the modulation factor using a polarized source, for removing non interesting bright sources in the field of view and for observing very bright celestial sources. The on-board …

Particle-Laden Turbulent Channel Flow with Wall-Roughness

2015

Turbulent flows transporting a dispersed-phase are found in many environmental applications and engineering devices. Particle-laden flows are characterized by several peculiar phenomenologies such as preferential particle concentration and turbulence modulation of the carrier-phase due to the presence of the inertial particles [1].

A classification of C-Fuchsian subgroups of Picard modular groups

2017

Through-focus response of multifocal intraocular lenses evaluated with a spatial light modulator

2012

A new testing technique based on the use of a liquid crystal spatial light modulator (SLM) is proposed to analyze the optical quality of multifocal intraocular lenses (MIOLs). Different vergences and decentrations of the incident beam can be programmed onto the SLM in order to record the point spread function (PSF) for different object positions. From these axial PSFs, the through-focus modulation transfer function is computed. Because there are no moving parts in the experimental setup, this method is fast and versatile to assess MIOLs. Experimental results confirm the potential of the proposed method.

Wavefront Recovery: Shack-Hartmann Aberrometry vs PhaseLift Using a Single Binary Amplitude Modulating Mask

2019

We investigate whether a wavefront can be recovered by using a single mask rotated in four different positions. Results show that PhaseLift can recover the wavefront from intensity measurements using such a kind of modulation.

Nonlinear polarization effects in optical fibers: polarization attraction and modulation instability [Invited]

2014

We review polarization stabilization techniques based on the polarization attraction effect in low-birefringence fibers. Polarization attraction or pulling may be based on cross-polarization modulation, on parametric amplification, and on Raman or Brillouin scattering. We also review methods for laser frequency conversion based on polarization modulation instabilities in low- and high-birefringence fibers, and photonic crystal fibers. Polarization instabilities in nonlinear fibers may also be exploited for sensing applications.

Infrared linear dichroism spectroscopy by a double modulation technique

1990

A linear IR dichroism experiment has been devised using a FTIR instrument in combination with a photoelastic modulator. Based on the Mueller-Stokes calculus, a method to directly obtain the absorbance spectra Av parallel and Av perpendicular from the modulated interferogram is developped, which allows the sensitive evaluation of the dichroic ratio. The photoelastic modulator, in combination with a FTIR instrument, offers high sensitivity, high speed, excellent signal to noise ratio and a broad spectral range from 3300 to 850 cm-1. First experimental results obstained from SBS block copolymer are reported.