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Results for “Optical Devices”

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At least 235 records · Page 13Linked to original sources
PubMed2006

Electro-optic multimode interference device using organic materials.

We present experimental results verifying the optical robustness of a 1 x 1 multimode interference (MMI) device that is directly butt coupled with optical fibers at 70 degrees C for 1050 h and discuss the gradual increase of polarization dependent loss. Based on this structure, an electro-optic (EO) MMI waveguide device that can control the output optical power by using an electrode structure located directly on top of the multimode is presented. As a proof of principle, we demonstrate the switching operation of the EO-MMI device using commercially available chromophore as the active EO material.

Journal Article↗
PubMed1999

A comparative study of the Podotrack, a simple semiquantitative plantar pressure measuring device, and the optical pedobarograph in the assessment of pressures under the diabetic foot.

AIMS: To test the Podotrack, a simple inexpensive semiquantitative footprint mat, for potential use as a screening tool for high plantar pressures, against the optical pedobarograph (a computerized device). METHODS: The Podotrack was superimposed on the pedobarograph for simultaneous measurement of pressures from both systems. Three independent observers quantified the pressures of Podotrack footprints from healthy controls and diabetic patients, both before (n=164) and after (n=183) training. The sensitivity of the Podotrack to identify high pressure areas measured by the pedobarograph (> 12.3 kg/cm2) was 78.7%, 45.8% and 44.3% (observer A, B and C) before training, but improved to 96.2%, 92.4% and 91.1% after training (P<0.01). Specificity for all three observers was more than 90% before and after training. Inter-observer agreement improved significantly after training (P<0.001). CONCLUSION: After a simple training of the observers, the Podotrack identified approximately all high pressure areas, suggesting that the Podotrack could be a useful screening tool to identify areas at risk of ulceration in diabetic patients. We recommend a standard training package for new Podotrack users, to optimize identification of diabetic patients at risk of foot ulceration.

Case-Control Studies↗
PubMed2002

Near-IR tunable laser with an integrated LiTaO3 electro-optic deflector.

We report the successful demonstration of a near-IR tunable laser (1525.4-1558.2 nm) that uses an integrated LiTaO3 deflector in combination with a reflection grating as an electronically tunable filter. The electro-optic deflector is a unique integrated optical device and consists of a horn-shaped array of electro-optic prisms in series. The almost 33 nm of tuning covers a wavelength region of high interest to the communications industry (1527-1550 nm).

Journal Article↗
PubMed2006

A bright future for organic field-effect transistors.

Field-effect transistors are emerging as useful device structures for efficient light generation from a variety of materials, including inorganic semiconductors, carbon nanotubes and organic thin films. In particular, organic light-emitting field-effect transistors are a new class of electro-optical devices that could provide a novel architecture to address open questions concerning charge-carrier recombination and light emission in organic materials. These devices have potential applications in optical communication systems, advanced display technology, solid-state lighting and electrically pumped organic lasers. Here, recent advances and future prospects of light-emitting field-effect transistors are explored, with particular emphasis on organic semiconductors and the role played by the material properties, device features and the active layer structure in determining the device performances.

Journal Article↗
PubMed2002

Heterostructure photonic crystals: theory and applications.

A hybrid structure combining square and hexagonal photonic crystal lattices is presented. This structure, which we refer to as heterostructure, offers the ability to tailor, optimize, and match the band structure of different lattices. The availability of heterostructures in photonic crystals opens abroad range of possibilities for optical device development. In particular, heterostructure photonic crystals are well suited for the application of optical beam splitting (Y coupler) and combining. Numerical experiments performed by use of the finite-difference time-domain method are shown to illustrate the device implemented in both unistructure and heterostructure lattices.

Journal Article↗
PubMed2003

How light gets through periodically nanostructured metal films: a role of surface polaritonic crystals.

The physical origin of the enhanced optical transmission of periodically structured films related to surface plasmon polaritons is discussed from first principles. The enhancement of transmission through smooth, randomly rough and periodically nanostructured films is considered. Analysis shows that any metal (or dielectric) nanostructured film can exhibit enhanced transmission in certain spectral ranges corresponding to surface plasmon (or phonon) polariton Bloch mode states on a periodic structure. Resonant tunnelling via these states is responsible for the transmission enhancement. The properties of surface polaritonic crystals are analogous to those of photonic crystals and can find numerous applications for scaling down optical devices to nanometric dimensions as well as for designing novel nanostructured materials whose optical properties are determined by surface polariton interaction in a periodic structure.

Journal Article↗
PubMed2005

Evanescent field-based optical fiber sensing device for measuring the refractive index of liquids in microfluidic channels.

We report a simple optical sensing device capable of measuring the refractive index of liquids propagating in microfluidic channels. The sensor is based on a single-mode optical fiber that is tapered to submicrometer dimensions and immersed in a transparent curable soft polymer. A channel for liquid analyte is created in the immediate vicinity of the taper waist. Light propagating through the tapered section of the fiber extends into the channel, making the optical loss in the system sensitive to the refractive-index difference between the polymer and the liquid. The fabrication process and testing of the prototype sensing devices are described. The sensor can operate both as a highly responsive on-off device and in the continuous measurement mode, with an estimated accuracy of refractive-index measurement of approximately 5 x 10(-4).

Complex Mixtures↗
PubMed2006

[Application of a jaw motion tracking device that measures six degrees of freedom using optoelectronic].

PURPOSE: A jaw motion tracking device that measures six degrees of freedom has recently been developed. Understanding jaw motion is useful, but previous measurement methods were impractical for use in dental clinics. The overall aim of this study was to demonstrate the simple operation, low cost, and high precision of a recently developed jaw tracking device. In addition, this study explored its potential clinical applications. METHODS: In this study, we compared two jaw motion tracking devices: a digital system type of device and an optical type of device. First we established a baseline occlusal plane from which to measure jaw motion in the same subject with both devices. The jaw motion signals were sampled at a frequency of 100 Hz. The subjects were three healthy women (mean age +/- SD = 26.3 +/- 1.2 years) who were recruited from among the crown-and-bridge faculty of Tsurumi University of Dentistry. The jaw motions measured were open-close movement, sagittal border movement, and frontal border movement. In addition, the kinematic axis point was calculated from the sagittal border movement. Data from the digital system type of device and data from the optical device were compared. The data were selected to measure rotation and translocation, i.e. jaw position about protrusion, both laterotrusion and maximal opening of the mouth. RESULTS: The root mean square (RMS) error of position measurement was 0.163 mm with MM-JI-E and 0.178 mm with the optical type of device. The RMS error of jaw motion measurement with the optical type of device was maximum at 0.8mm and minimum at 0.1mm. This was similar to that with digital system type of jaw motion tracking device. CONCLUSION: This study showed the possibility of developing clinical applications for this jaw motion device.

Adult↗
PubMed2005

Expanding the bandwidth of slow-light photonic devices based on coupled resonators.

It is shown theoretically that canceling third-order dispersion can substantially increase the useful bandwidths of linear and nonlinear optical devices based on slow propagation of light. Cancellation on both global and local scales can be achieved by combination of the ring-based coupled resonator lines and all-pass optical filters.

Journal Article↗
PubMed2004

The Ion Conveyor. An ion focusing and conveying device.

The control and transmission of ions or small charged droplets in the intermediate to high-pressure regime is of primary importance in areas such as atmospheric pressure ionisation. Where small apertures separate differentially pumped vacuum regions in the inlet systems to mass spectrometers, a large proportion of the available ion current is lost to the surrounding electrode structures. A new ion-optical device, named the ion conveyor, incorporating electrodynamic focusing and conveying of charged entities is described. Results from ion-optical simulations are presented demonstrating the performance of the device in various operating modes and electrode configurations.

Journal Article↗
PubMed2000

Trapping and emission of photons by a single defect in a photonic bandgap structure

By introducing artificial defects and/or light-emitters into photonic bandgap structures, it should be possible to manipulate photons. For example, it has been predicted that strong localization (or trapping) of photons should occur in structures with single defects, and that the propagation of photons should be controllable using arrays of defects. But there has been little experimental progress in this regard, with the exception of a laser based on a single-defect photonic crystal. Here we demonstrate photon trapping by a single defect that has been created artificially inside a two-dimensional photonic bandgap structure. Photons propagating through a linear waveguide are trapped by the defect, which then emits them to free space. We envisage that this phenomenon may be used in ultra-small optical devices whose function is to selectively drop (or add) photons with various energies from (or to) optical communication traffic. More generally, our work should facilitate the development of all-optical circuits incorporating photonic bandgap waveguides and resonators.

Journal Article↗
PubMed1980

Optoelectronic transducer for in vivo recording of oviductal contractile activity.

An optoelectronic instrument to record oviductal muscular activity in chronically instrumented animals was evaluated in in vitro and in vivo experiments. The intensity of red light transmitted through the oviduct was modulated by contractions of the oviductal wall producing an optical analog of the mechanical events. Accuracy of the analog was tested by Fourier analysis of signals from mechanical and optoelectronic transducers placed at the same site on the oviduct; the results validated the use of the optical device as a contraction event sensor. Contractions of the tubal mesenteries had less effect on the optical signal than on signals from extraluminal mechanical transducers. Optical and photographic recordings of luminal transport in exposed oviducts showed a correspondence of intraluminal movements to events in the optical contraction signal. This instrument does not alter tubal function, and thus it is an especially useful experimental tool to investigate the role of oviductal muscular activity in fertility.

Animals↗
PubMed2005

Resonant nano-cluster devices.

The resonance-enhanced absorption (REA) by metal clusters on a surface is an effective technique on which to base bio-optical devices. A four-layer device consisting of a metal mirror, a polymer or glass-type distance layer, a biomolecule interaction layer and a sub-monolayer of biorecognitively bound metal nano-clusters is reported. Experiments indicate a strong influence of the resonator homogeneity on the absorption maximum. Layer stability plays an important role in the overall performance of the device. Techniques and optimised lab protocols to set up biochips that use the REA process in the detection are presented. The sensors show one to three narrow reflection minima in the visible and or infra-red (IR) part of the spectrum and therefore they do not suffer from the spectral limitations associated with spherical gold colloids. Metal clusters (synthesised by thermal step reduction) as well as metal- dielectric shell clusters (synthesised by various shell deposition processes) are used to precisely shift the readout of the device to any frequency in the visible and near IR range. Disposable single-step protein chips, DNA assays as well as complex biochip arrays are established that use various DNARNA, antigen-antibody and protein-protein interaction systems.

Biosensing Techniques↗
PubMedDate not supplied

Bronchoscopy with the Vision Sciences BF100 disposable-sheath device: French experience after 328 procedures.

BACKGROUND: In spite of adhesion to recommended disinfection procedures, the transmission of infections by bronchoscopes is a permanent problem. OBJECTIVE: The new device may prevent nosocomial infections because it consists of two parts: a specific bronchoscope Vision Sciences BF100 and a single-use protective sheath for each procedure. The aim of this paper is to report our practice and the difficulties encountered when using this system. METHODS: We report our experience from 1997 to 2002 after 328 elective and emergency endoscopic procedures with the BF100 device. In a retrospective study, we describe the population and the incidents during procedure. We discuss the impact of the use of BF100 on the cost of bronchoscopies. RESULTS: The major constraint is the care required in assembling the optical device and disposable sheath. The intrinsic qualities of the optics are confirmed; any sample may be taken although image quality and suction capacity are inferior to videoscopes. Maneuverability is inferior to videoscopes, but improves with a short experience. In addition, this device is expensive. CONCLUSIONS: The technical performances of the BF100 device are inferior to those of videoscopes but the concept of sterile single-use sheaths is able to prevent the nosocomial infections related to bronchoscopes. Because of the cost, examination with the BF100 should be reserved to patients with proved or suspected infection (multiresistant bacteria, tuberculosis, hepatitis C and B virus, HIV, prions) and immunosuppression (hematologic diseases).

Asepsis↗
PubMed2026

Morphology-Encoded Colorimetric Hydrogen Sensing Using Embedded Reactive Pd Absorbers in Fabry-Perot Cavities.

Chemical reactions offer a powerful strategy for generating visible optical responses through localized changes in absorption, dielectric environment, and interfacial wetting. A palladium (Pd)-embedded Fabry-Perot cavity is introduced as a reaction-active optical platform in which structural color is governed by intracavity absorption coupled with reaction-induced dielectric perturbation. Positioning Pd within the dielectric spacer creates a spatially controllable reactive absorber whose vertical location relative to the standing-wave field dictates wavelength-selective absorption within the cavity. The morphology of the embedded Pd layer provides an additional design parameter by modulating both optical loss and interfacial wetting. Under hydrogen exposure in the presence of oxygen, catalytic water formation at the Pd/polymer interface generates localized dielectric heterogeneity and interfacial water droplets, thereby perturbing the optical path length and amplifying the visible response. As a result, the cavity exhibits pronounced, morphology-dependent color transitions that are inaccessible through dielectric-layer engineering or Pd/PdH refractive-index changes alone, enabling direct visual hydrogen sensing under ambient light, as well as flexible optical devices capable of large-area patterning. These findings establish a design framework for reaction-active optical cavities that translate localized chemistry into a colorimetric hydrogen sensing mechanism.

Fabry&#x2013;Perot resonator↗
PubMed2006

Elliptical concentrators.

Nonimaging optics is a field devoted to the design of optical components for applications such as solar concentration or illumination. In this field, many different techniques have been used to produce optical devices, including the use of reflective and refractive components or inverse engineering techniques. However, many of these optical components are based on translational symmetries, rotational symmetries, or free-form surfaces. We study a new family of nonimaging concentrators called elliptical concentrators. This new family of concentrators provides new capabilities and can have different configurations, either homofocal or nonhomofocal. Translational and rotational concentrators can be considered as particular cases of elliptical concentrators.

Journal Article↗
PubMed2002

Biosensors: new approaches in drug discovery.

The development of biosensors for analytical purposes has attracted a great deal of attention in recent years. A biosensor is defined as an analytical device consisting of a biological component (e.g., enzyme, antibody, entire cell, DNA) and a physical transducer (e.g., electrode, optical device). Biosensors are mostly designed for routine analysis, such as clinical diagnosis, quality control of food, in-process control of fermentations, and in environmental analysis. Many of these sensors are also suitable for screening purposes in order to find new drugs. Such systems should yield information either about compounds with known bioactivity or about the bioactivity of samples with known or unknown chemical composition. Biosensors intended for the latter purpose are essentially based on whole cells carrying receptors and ion channels at their surfaces. Miniaturization of structures, primarily based on silicon, allows integration of many sensors into arrays, which may be suitable for the screening of natural and chemical products as well as combinatorial libraries. Until now, no commercially available sensors of this kind exist but they are expected in the near future. Different biosensors, based on enzymes, antibodies, cells, artificial membranes and entire animal tissues, which can be used in drug discovery and may lead to efficient screening systems in the future, are described in this review.

Animals↗
PubMed2005

All-optical switching in silicon photonic crystal waveguides by use of the plasma dispersion effect.

Silicon photonic crystals offer new ways of controlling the propagation of light as well as new tools for the realization of high-density optical integration on monolithic substrates. However, silicon does not possess the strong nonlinearities that are commonly used in the dynamic control of optical devices. Such dynamic control is nevertheless essential if silicon is to provide the higher levels of functionality that are required for optical integration. We demonstrate that the combination of the refractive index change caused by the presence of photoexcited carriers, or so-called plasma dispersion, and photonic crystal properties such as photonic bandgaps, constitutes a powerful tool for active control of light in silicon integrated devices. We show close to 100% modulation depth near the photonic crystal band edge.

Journal Article↗