Search results for "Note"
showing 10 items of 10709 documents
Resonant Beam Steering and Carpet Cloaking Using an Acoustic Transformational Metascreen
2018
International audience; We invoke the Huygens principle to derive dispersion characteristics of acoustic transformational meta-surfaces that can deflect parallel wavefronts in a desired direction. We also propose a dual-Lorentz resonator whose aperture fields can be tuned by geometrical changes to implement a particular phase with unity reflection coefficient. The proposed metascreen is designed by our arranging slightly detuned Lorentz cavities that generate the necessary interference to compensate for the incident wavefronts. Since a complete 0-2 pi range of the reflection phase is achieved, the metascreen can steer a beam across the full horizon. Moreover, since the proposed dual resonat…
Towards an efficient epsilon near-zero-based wavefront shaper
2017
Although epsilon-near-zero (ENZ) metamaterials offer many unconventional ways to play with light, the optical impedance mismatch with surroundings can limit the efficiency of future devices. An original example of ENZ-based applications is the wavefront shaping, but up to now devices have transmission efficiency as low as 10-5 [1]. Here, we report strategies to enhance the transmittance through ENZ layer and we demonstrate an enhancement by four orders of magnitude of the transmittance, which reaches up to 15% in the context of ENZ-based wavefront shaping [2].
Improving the transmittance of an epsilon-near-zero-based wavefront shaper
2016
Although Epsilon-Near-Zero metamaterials (ENZ) offer many unconventional ways to play with light, the optical impedance mismatch with surroundings can limit the efficiency of future devices. We report here on the improvement of the transmittance of an Epsilon-Near-Zero (ENZ) wavefront shaper. We first address in this paper the way to enhance the transmittance of a plane wave through a layer of ENZ material thanks to a numerical optimization approach based on the Transfer Matrix Method. We then transpose the one dimensional approach to a two dimensional case where the emission of a dipole is shaped into a plane wave by an ENZ device with a design that optimizes the transmittance. As a result…
Off-axis digital holographic multiplexing for rapid wavefront acquisition and processing
2020
Off-axis holographic multiplexing involves capturing several complex wavefronts, each encoded into off-axis holograms with different interference fringe orientations, simultaneously, with a single camera acquisition. Thus, the multiplexed off-axis hologram can capture several wavefronts at once, where each one encodes different information from the sample, using the same number of pixels typically required for acquiring a single conventional off-axis hologram encoding only one sample wavefront. This gives rise to many possible applications, with focus on acquisition of dynamic samples, with hundreds of scientific papers already published in the last decade. These include field-of-view multi…
Control of spontaneous spiral formation in a zwitterionic micellar medium
2011
The transition from planar fronts, trigger waves or solitary pulses to spirals in excitable media, has attracted increasing interest in the past few decades, mainly because of its relevance for biological and medical applications. In this paper we describe a new and convenient method for spiral generation starting from symmetric wavefronts. By using the micelle-forming zwitterionic surfactant N-tetradecyl- N,N-dimethylamine oxide in a Belousov–Zhabotinsky solution, it is possible to control to a large extent the domains where spirals can be spontaneously generated. The mechanism responsible for the wavefront break up lies in the interaction of the propagating waves with the unexcitable regi…
Experimental validation of a customized phase mask designed to enable efficient computational optical sectioning microscopy through wavefront encodin…
2017
In this paper, wavefront-encoded (WFE) computational optical sectioning microscopy (COSM) using a fabricated square cubic (SQUBIC) phase mask, designed to render the system less sensitive to depth-induced aberration, is investigated. The WFE-COSM system is characterized by a point spread function (PSF) that does not vary as rapidly with imaging depth compared to the conventional system. Thus, in WFE-COSM, image restoration from large volumes can be achieved using computationally efficient space-invariant (SI) algorithms, thereby avoiding the use of depth-variant algorithms. The fabricated SQUBIC phase mask was first evaluated and found to have a 75% fidelity compared to the theoretical desi…
Leakage radiation microscopy of surface plasmon coupled emission: investigation of gain-assisted propagation in an integrated plasmonic waveguide.
2010
International audience; Using a single-mode dielectric-loaded surface plasmon polariton waveguide doped with quantum dots, we were able to slightly increase the propagation length of the mode by stimulated emission of plasmon. We analyse the amplification phenomenon in the visible range by combining leakage radiation microscopy and surface plasmon coupled emission techniques.
Performance of electro-optical plasmonic ring resonators at telecom wavelengths
2012
International audience; In this work we report on the characteristics of an electro-optical dielectric-loaded surface plasmon polariton waveguide ring resonator. By doping the dielectric host matrix with an electro-optical material and designing an appropriate set of planar electrodes, we measured a 16% relative change of transmission upon application of a controlled electric field. We have analyzed the temporal response of the device and conclude that electrostriction of the host matrix is playing a dominating role in the transmission response.
Efficient excitation of dielectric-loaded surface plasmon-polariton waveguide modes at telecommunication wavelengths
2008
International audience; The excitation of surface plasmon-polariton (SPP) waveguide modes in subwavelength dielectric ridges deposited on a thin gold film has been characterized and optimized at telecommunication wavelengths. The experimental data on the electromagnetic mode structure obtained using scanning near-field optical microscopy have been directly compared to full vectorial three-dimensional finite element method simulations. Two excitation geometries have been investigated where SPPs are excited outside or inside the dielectric tapered region adjoint to the waveguide. The dependence of the efficiency of the SPP guided mode excitation on the taper opening angle has been measured an…
Vacuum Rabi Splitting and Strong-Coupling Dynamics for Surface-Plasmon Polaritons and Rhodamine 6G Molecules
2009
We report on strong coupling between surface plasmon polaritons (SPP) and Rhodamine 6G (R6G) molecules, with double vacuum Rabi splitting energies up to 230 and 110 meV. In addition, we demonstrate the emission of all three energy branches of the strongly coupled SPP-exciton hybrid system, revealing features of system dynamics that are not visible in conventional reflectometry. Finally, in analogy to tunable-Q microcavities, we show that the Rabi splitting can be controlled by adjusting the interaction time between waveguided SPPs and R6G deposited on top of the waveguide. The interaction time can be controlled with sub-fs precision by adjusting the length of the R6G area with standard lith…