Interferometric measurements of electric field-induced displacements in piezoelectric thin films

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Long-range interactions and electric response are essential for accurate modeling of condensed-phase systems, but capturing them efficiently remains a challenge for atomistic machine learning. Traditionally, these two phenomena can be represented by static charges that underlie Coulomb interactions between atoms, and dynamic charges such as atomic polar tensors—aka Born effective charges—describing the response to an external electric field. We critically compare different approaches to learn both types of

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Multiferroic materials show, in a single phase, at least two ferroic properties. The latter are are (anti-)ferroelectricity, (anti-)ferromagnetism or (anti-)ferroelasticity. Interesting applications can use the properties of multiferroics, especially with those presenting magnetic and electric coupling. The ability of controlling a magnetic field with an electric field, using the magnetoelectric coupling, could have interesting applications in spintronics (spin transport electronics), electronic memory devi

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A classical technique to monitor dynamical processes at the single-molecule level is fluorescence correlation spectroscopy (FCS). However, FCS requires fluorescent labels that are typically limited by photobleaching and saturation. We present a new method, optical coherence correlation spectroscopy (OCCS), based on noble-metal nanoparticles that overcome those photobleaching and saturation limitations. OCCS is a correlation spectroscopy technique based on dark-field optical coherence microscopy (dfOCM), a F

High-Q, bulk acoustic wave composite resonators based on a symmetric layer sequence Of SiO2-A1N-SiO2 sandwiched between electrodes have been developed. Acoustic isolation was achieved by means of deep silicon etching to obtain membrane type TFBAR's. Three different device versions were investigated. The SiO2 film thicknesses was varied (70nm, 310mn and 770nm) while the piezoelectric A1N film had a constant thickness of 1.2 mu m. The sputter deposited A1N film grown on the amorphous, sputter deposited SiO2 l

Digital holographic microscopy (DHM) is an interferometric technique, providing quantitative mapping of the phase shift induced by semi- transparent microscopic specimens, such as cells, with sub-wavelenght resolution along the optical axis. Thanks to actual PCs and CCDs, DHM provides nowadays cost-effective instruments for real-time measurements at very high acquisition rates, with sub-micron transverse resolution. However, DHM phase images do not reveal the three-dimensional (3D) internal distribution of

Magnetic Resonance Imaging (MRI) is nowadays a widely used medical tool, as it is a non-invasive and non-harmful way to study inner soft tissues. One of the characteristics of this method is the bias field, also called Intensity In-homogeneity (IIH), which is an artifact that affects quantitative image analysis consisting in a low frequency variation of the brightness through all the image acquired. This undesired effect makes difficult medical functions such as visual inspection or also intensity-based seg

The invention relates to an interferometer system (41), especially for use in a co-ordinate measuring system. Said interferometer system comprises, disposed in an illumination beam path, a pair of spaced-apart boundary surfaces (52, 53). A boundary surface (53) facing an object (9) is arranged in a detection beam path, a detector (61) being additionally disposed in said detection beam path. The invention also relates to an interferometer system, especially one of the above-described type, which is provided

Optical Coherence Tomography (OCT), a well-established imaging method based on low-coherence interferometry, provides cross-sectional images of the internal structure of biological samples with a resolution in the micrometer range. OCT was successfully applied on various tissues such as for instance the retina, the skin or a tooth. In highly scattering tissues like the skin, probing depth is limited to approximately 2mm, mainly due to insufficient rejection of multiply scattered light. Presently, the contri

Homogeneous electric fields are treated within density functional calculations with periodic boundary conditions. A nonlocal energy functional depending on the applied field is used within an ab initio molecular dynamics scheme. The reliability of the method is demonstrated in the case of bulk MgO for the Born effective charges, and the high- and low-frequency dielectric constants.

The accepted model for light emission and propagation in organic LEDs (OLED) which consists of several optically thin functional layers deposited on a thick substrate is a classical dipole located in the emitting layer. The propagation of the emitted light is commonly described by a Fourier expansion of the dipole field into plane waves which represent the various radiating and bound modes of the layered structure in k-space. To calculate the electric and magnetic fields inside and outside the LED an integr

Systems with a ferroelectric to paraelectric transition in the vicinity of room temperature are useful for devices. Adjusting the ferroelectric transition temperature (T-c) is traditionally accomplished by chemical substitution - as in BaxSr1-xTiO3, the material widely investigated for microwave devices in which the dielectric constant (epsilon(r)) at GHz frequencies is tuned by applying a quasi-static electric field(1,2). Heterogeneity associated with chemical substitution in such films, however, can broad

Current spectroscopic optical coherence tomography (OCT) methods rely on a posteriori numerical calculation. We present an experimental alternative for accessing spectroscopic information in OCT without post-processing based on wavelength de-multiplexing and parallel detection using a diffraction grating and a smart pixel detector array. Both a conventional A-scan with high axial resolution and the spectrally resolved measurement are acquired simultaneously. A proof-of-principle demonstration is given on a

In this work, new spectroscopic techniques have been developed to measure electric dipole moments of highly excited rovibrational states of small polyatomic molecules in the gas phase. These techniques make use of lasers arid of microwave synthesizers. They enable one to measure the change on a molecular system caused by applying an external electric field, which is called Stark effect and from this, extract the dipole moment. The first technique, called microwave Stark spectroscopy, makes use of microwave-

An optical fibre sensing technique for the measurement of dynamic deformations using a Michelson interferometer is reported. The method applied to interferometers with an initial path unbalance of around 1 cm is based on the rf intensity modulation of a low-coherence source. A large measurement range of 1 cm is intrinsic to the method and with an adequate demodulation process sensitivity better than 10 μm is obtained. This novel approach allows for measuring dynamic deformations with a bandwidth up to 100 H

PZT (PbZrx Ti1-xO3) thin films have been locally grown by means of sol-gel deposition and local annealing on microhotplates. The microhotplates were based on a stress compensated Si3N4 /SiO2 membranes as structural elements and contained tantalum silicide filaments (Ta5Si3) for resistive heating. Above the filaments, a passivation layer of SiO2, an adhesion layer of Ti/TiO2 and a bottom electrode of Pt were deposited. Due to the low heat conductivity of the membrane, crystallization of the PZT film occurs e

There is a real need for methods to allow the measurement of the form and deformation of large objects. For example, for maintenance and production costs as well as for security. Even though there are many methods of measuring the form and deformation of small objects (up to 1 m2), currently none of them are able to quickly measure larger objects (i.e. at a large number of points at the same time). Among the existing techniques, the fringe projection seem to us one of the most adequate to deal with these ki

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Interferometric measurements of electric field-induced displacements in piezoelectric thin films

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