Search results for "ELECTRONICS"

Designing an x-ray baffle for stray-light reduction at the focal plane of the Wide Field Imager on board EDGE

2008

We exploited a ray-tracing Montecarlo code to investigate the effects of stray-light on the performances of the Wide Field Imager (FoV = 1.5 deg) on board the EDGE satellite. We found non negligible stray-light contamination up to ~ 8 deg off-axis angles. We discuss the benefits of a baffle in order to reduce this contamination, that would strongly affect the telescope sensitivity, and present two possible baffle designs based on results of simulations.

Synchronized photonic modulators driven by surface acoustic waves

2013

Photonic modulators are one of the most important elements of integrated photonics. We have designed, fabricated, and characterized a tunable photonic modulator consisting of two 180 degrees-dephased output waveguide channels, driven by a surface acoustic wave in the GHz frequency range built on (Al,Ga)As. Odd multiples of the fundamental driven frequency are enabled by adjusting the applied acoustic power. A good agreement between theory and experimental results is achieved. The device can be used as a building block for more complex integrated functionalities and can be implemented in several material platforms. (C) 2013 Optical Society of America

Delocalization of Nonlinear Optical Responses in Plasmonic Nanoantennas

2015

Remote excitation and emission of two-photon luminescence and second-harmonic generation are observed in micrometer long gold rod optical antennas upon local illumination with a tightly focused near-infrared femtosecond laser beam. We show that the nonlinear radiations can be emitted from the entire antenna and the measured far-field angular patterns bear the information regarding the nature and origins of the respective nonlinear processes. We demonstrate that the nonlinear responses are transported by the propagating surface plasmon at excitation frequency, enabling thereby polariton-mediated tailoring and design of nonlinear responses.

Near-field beam displacement at surface plasmon resonance

2011

International audience; A finite-size beam exciting a surface plasmon polariton (SPP) in a prism coupling configuration experiences an in-plane displacement that can be used for the characterization of plasmonic components by means of near-field optical microscopy. We first demonstrate experimentally the existence of this displacement by taking near-field images of finite-width metal strips. Next, the properties of this shift are analyzed in detail. We investigate the dynamic of the near-field shift for an incident Gaussian beam as a function of illumination conditions. For beams with a narrow spectrum, we propose a straightforward derivation showing that the displacement depends on the ave…

Counter-propagating difference frequency mixing in diamond with terahertz waves

2013

We investigate four-wave mixing between terahertz and optical pulses in diamond. We observe the occurrence of sum and difference frequency generation, with the latter being phase-matched for terahertz pulses counter-propagating to the optical field.

A broadband multifocal metalens in the terahertz frequency range

2016

Abstract Metasurfaces, the 2D form of metamaterials with their ability in phase, amplitude and polarization manipulation are widely used in designing optical devices. Efforts to find proper photonic components in the terahertz (THz) range of frequency lead us to adopt metasurfaces as their constituent elements. Here, we conceived a broadband THz lens with an adjustable number and arrangement of focal points. To have a full control over the lens functionality, we used a metasurface with the capability of simultaneously modulating the amplitude and phase of the incident wave. C-shaped ring resonators (CSRRs) with different geometry and orientation capable of simultaneously manipulating phase …

Tapered Two-Wire Waveguide for Time-Domain Integration of Broadband Terahertz Pulses

2021

We show the time-domain integration of terahertz pulses achieved in a sub-wavelength, tapered two-wire waveguide. Both simulation and experimental results prove the time integration functionality of this waveguide topology.

Spatio-temporal control of ultra-short pulses by using diffractive optical elements

2012

Diffractive optical elements (DOEs) have shown their applicability to control the spatio-temporal characteristics of ultra-short laser pulses. DOEs can provide high efficiency, compactness, very low material dispersion and, when implemented with spatial light modulators, real-time pulse engineering. In this communication, we report management of temporal and spectral profiles of ultra-short pulses by means of a quasi-direct space-to-time (QDST) pulse shaper. Moreover, we present spatio-temporal control, including dispersion compensation, by DOEs, and applications for activating nonlinear processes. On the other hand, we have achieved complete spatial control of ultra-short pulses, overcomin…

Polarization-sensitive population trapping in an optically pumped laser

1994

Piezoelectric Actuated Nonlinear Energy Sink With Tunable Attenuation Efficiency

2019

Abstract Comparing to linear vibration absorbers, nonlinear energy sinks (NESs) have attracted worldwide attention for their intrinsic characteristics of targeted energy transfer or energy pumping in a relatively wide frequency range. Unfortunately, they are highly dependent on the vibration amplitude to be attenuated and will play its role only if the external load exceeds a specific threshold value. Different from the passive bistable NES, a novel piezoelectric nonlinear energy sink (PNES) is designed by introducing in-phase actuation to compensate or enhance the external vibration loads, thus triggering the NES operating in high attenuation efficiency. The nonlinear mathematic model of t…