Search results for "Object-relational impedance mismatch"

showing 3 items of 3 documents

Reverberation reduction in capacitive micromachined ultrasonic transducers (CMUTs) by front-face reflectivity minimization

2015

Abstract Front-face acoustic reflectivity of ultrasonic imaging transducers, due to acoustic impedance mismatch with the propagation medium, may cause reverberation phenomena during wideband pulse-echo operation. Front-face reflectivity may be reduced by promoting the transmission of the echoes, received from the medium, to the transducer backing, and by maximizing the mechanical-to-electrical energy conversion and dissipation by tuning the electrical load impedance connected to the transducer. In Capacitive Micromachined Ultrasonic Transducers (CMUTs), the energy transfer from the medium to the backing is very low due to the large impedance mismatch between the medium and the transducer su…

Microelectromechanical systemsMaterials scienceCMUTTransducer reflectivityAcousticsReverberationPhysics and Astronomy(all)DissipationCapacitive Micromachined Ultrasonic Transducer (CMUT)MEMSCapacitive micromachined ultrasonic transducersTransducerObject-relational impedance mismatchReverberation; Transducer reflectivity; Capacitive Micromachined Ultrasonic Transducer (CMUT); MEMSAcoustic impedanceElectrical impedanceMicrofabrication
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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].

WavefrontPhysicsbusiness.industryMetamaterialContext (language use)02 engineering and technology021001 nanoscience & nanotechnology01 natural sciences010309 opticsOpticsTransmission (telecommunications)Orders of magnitude (time)0103 physical sciencesTransmittanceObject-relational impedance mismatchOptoelectronics0210 nano-technologybusinessElectrical impedance2017 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC)
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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…

WavefrontPhysicsbusiness.industryOrders of magnitude (temperature)Transfer-matrix method (optics)Plane waveFOS: Physical sciencesPhysics::OpticsMetamaterial02 engineering and technology021001 nanoscience & nanotechnology01 natural sciencesAtomic and Molecular Physics and OpticsOpticsTranspose0103 physical sciencesObject-relational impedance mismatchTransmittance010306 general physics0210 nano-technologybusinessOptics (physics.optics)Physics - OpticsOptics Letters
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