Search results for "Physics::Optics"
showing 10 items of 1958 documents
Surface Acoustic Waves Propagation at Lossy Metasurfaces: Experimental and Theoretical Characterization of Complex Dispersion Relations
2016
International audience; While metasurfaces properties are known to govern the dispersion relation of Surface Acoustic Wave (SAW) that mimics surface plasmon phenomena, little attention has been paid to the effects of micro-structural dissipation on that dispersion relation. Here we report the experimental and theoretical characterization of both SAW propagation and attenuation in the presence of a lossy metasurface. The latter consists of quarter-wavelength resonators embedded in a rigid board and arranged periodically in a square lattice. Complex SAW wavenumbers are retrieved experimentally using a spatial Laplace Transform, and experimental results are compared with those from an analytic…
Extensive tailorability of sound absorption using acoustic metamaterials
2017
We present an experimental demonstration of sound absorption tailorability, using acoustic metamaterials made of resonant cavities that does not rely on any dissipative material. As confirmed by numerical calculation, we particularly show that using quarter-wave-like resonators made of deep subwavelength slits allows a high confinement of the acoustic energy of an incident wave. This leads to enhance the dissipation in the cavities and, consequently, generates strong sound absorption, even over a wide frequency band. We finally demonstrate experimentally the key role of the filling ratio in tailoring such an absorption, using a metamaterial constituted of space-coiled cavities embedded in a…
Optical force rectifiers based on PT-symmetric metasurfaces
2018
We introduce here the concept of optical force rectifier based on parity-time symmetric metasurfaces. Directly linked to the properties of non-Hermitian systems engineered by balanced loss and gain constituents, we show that light can exert asymmetric pulling or pushing forces on metasurfaces depending on the direction of the impinging light. This generates a complete force rectification in the vicinity of the exceptional point. Our findings have the potential to spark the design of applications in optical manipulation where the forces, strictly speaking, act unidirectionally. R.A. and B.G. would like to acknowledge financial support from the Max Planck Society. J.C. acknowledges the suppor…
Entangled photons through thick scattering media: experiments and comparison with simulations of the biphoton wave function
2021
International audience; We report experimentally and numerically quantum correlations imaging through thick random media. We demonstrated that spatial correlations between twin photon are still detected but no in form of two-photon speckle-like patterns.
Surface plasmon interference excited by tightly focused laser beams
2007
International audience; We show that interfering surface plasmon polaritons can be excited with a focused laser beam at normal incidence to a plane metal film. No protrusions or holes are needed in this excitation scheme. Depending on the axial position of the focus, the intensity distribution on the metal surface is either dominated by interferences between counterpropagating plasmons or by a two-lobe pattern characteristic of localized surface plasmon excitation. Our experiments can be accurately explained by use of the angular spectrum representation and provide a simple means for locally exciting standing surface plasmon polaritons.
Cavity Resonator Integrated Guided mode resonance Filter : Spectral & Modal Reflector
2015
International audience; CRIGF is a new generation of narrowband filter. It consists of subwavelength gratings nearby or upon a waveguide. At the center, a small GMRF (Guided Mode Resonance Filter) or GC (Grating Coupler) coupled radiated & guided mode, then, DBR (Distributed Bragg Reflector) at each side localise mode inside a horizontal Fabry-Pérot cavity. Two PS (Phase sections) are use to fine tune the Fabry-Pérot modes with the grating coupler.
Dipolar and quadrupolar plasmon LASER modes for core-shell
2012
International audience; Spasers are based on a combination of the localized plasmon field properties of the metallic material with an amplification medium [1]. The optical properties of these compound systems are based on a compensation of the metallic losses trough the optical gain of the amplification medium. Recently it was demonstrated experimentally that coating a gold nanoparticle with a silica shell containing Oregon Green 488 allows to overcome the loss-of-surface plasmon resonance [2]. One of the consequences of the compensation of the losses is an extremely large enhancement of the local field amplitudes (giant resonances). Rising the gain leads to a singularity stricking the tran…
On chip shapeable optical tweezers
2013
International audience; Particles manipulation with optical forces is known as optical tweezing. While tweezing in free space with laser beams was established in the 1980s, integrating the optical tweezers on a chip is a challenging task. Recent experiments with plasmonic nanoantennas, microring resonators, and photonic crystal nanocavities have demonstrated optical trapping. However, the optical field of a tweezer made of a single microscopic resonator cannot be shaped. So far, this prevents from optically driven micromanipulations. Here we propose an alternative approach where the shape of the optical trap can be tuned by the wavelength in coupled nanobeam cavities. Using these shapeable …
Residual Phase Noise Measurement of Optical Second Harmonic Generation in PPLN Waveguides
2017
We report on the characterization, including residual phase noise and fractional frequency instability, of fiber-coupled PPLN non-linear crystals. These components are devoted to frequency doubling 871 nm light from an extended-cavity diode laser to produce a 435.5 nm beam, corresponding to the ytterbium ion electric quadrupole clock transition. We measure doubling efficiencies of up to 117.5 %/W. Using a Mach-Zehnder interferometer and an original noise rejection technique, the residual phase noise of the doublers is estimated to be lower than ${\rm -35\, dBrad^2/Hz}$ at 1 Hz, making these modules compatible with up-to-date optical clocks and ultra-stable cavities. The influence of externa…
On the performance of wavelength meters : Part 1 : consequences for medium-to-high-resolution laser spectroscopy
2020
Present-day laser-spectroscopy experiments increasingly rely on modern commercial devices to monitor, stabilize, and scan the wavelength of their probe laser. Recently, new techniques are capable of achieving unprecedented levels of precision on atomic and nuclear observables, pushing these devices to their performance limits. Considering the fact that these observables themselves are deduced from the frequency difference between specific atomic resonances, in the order of MHz–GHz, the uncertainty on the output of the device measuring the wavelength is often directly related to the final systematic uncertainty on the experimental results. Owing to its importance, the performance of several …