Search results for " light"
showing 10 items of 1141 documents
Parabolic pulse generation with active or passive dispersion decreasing optical fibers
2007
International audience; We experimentally demonstrate the possibility to generate parabolic pulses via a single dispersion decreasing optical fiber with normal dispersion. We numerically and experimentally investigate the influence of the dispersion profile, and we show that a hybrid configuration combining dispersion decrease and gain has several benefits on the parabolic generated pulses.
Design and Implementation of Density Sensor for Liquids Using Fiber Bragg Grating Sensor
2022
In this paper, an optical fiber sensor based density sensor is proposed and demonstrated experimentally. The sensor is formed by fiber Bragg grating (FBG) sensor. The proposed sensor design is very simple and versatile for density measurements of liquids. The FBG strain sensor has one end mounted to a 3D printed rigid support, and the other end connected to a 3D manufactured clamp in this sensor design. A metal ball is suspended from this clamp by a non-stretchable cord. When it is completely immersed in liquid, the liquid buoyancy force acts on it. As a result, the strain in FBG varies depending on the force applied to the ball. This results in a wavelength shift in the FBG sensor. The pro…
Comparison of two portable solid state detectors with an improved collimation and alignment device for mammographic x-ray spectroscopy
2006
We describe a portable system for mammographic x-ray spectroscopy, based on a 2 X 2 X 1 mm3 cadmium telluride (CdTe) solid state detector, that is greatly improved over a similar system based on a 3 X 3 X 2 mm3 cadmium zinc telluride (CZT) solid state detector evaluated in an earlier work. The CdTe system utilized new pinhole collimators and an alignment device that facilitated measurement of mammographic x-ray spectra. Mammographic x-ray spectra acquired by each system were comparable. Half value layer measurements obtained using an ion chamber agreed closely with those derived from the x-ray spectra measured by either detector. The faster electronics and other features of the CdTe detecto…
High Quality Factor Silicon Membrane Metasurface for Intensity-Based Refractive Index Sensing
2021
We propose a new sensing device based on all-optical nano-objects placed in a suspended periodic array. We demonstrate that the intensity-based sensing mechanism can measure environment refractive index change of the order of 1.8×10−6, which is close to record efficiencies in plasmonic devices.
Efficient Polymer Light‐Emitting Diode Using Air‐Stable Metal Oxides as Electrodes
2009
Poly(phenylenevinylene)‐based organic light‐emitting diodes (OLEDs) are fabricated using air‐stable metal oxides as electrodes, producing very efficient and bright electroluminescent devices. Efficiencies of 8 cd A−1 and luminances above 20000 cd m−2 are obtained, comparable to the values reported for classic OLED structures using reactive metals as cathodes.
Improved noncontact optical sensor for detection of glucose concentration and indication of dehydration level.
2014
The ability to extract different bio-medical parameters from one single wristwatch device can be very applicable. The wearable device that is presented in this paper is based on two optical approaches. The first is the extraction and separation of remote vibration sources and the second is the rotation of linearly polarized light by certain materials exposed to magnetic fields. The technique is based on tracking of temporal changes of reflected secondary speckles produced in the wrist when being illuminated by a laser beam. Change in skin’s temporal vibration profile together with change in the magnetic medium that is generated by time varied glucose concentration caused these temporal chan…
Continuous-wave dual-wavelength operation at 1062 and 1338nm in Nd3+:YAl3(BO3)4 and observation of yellow laser light generation at 592nm by their se…
2009
Abstract We report simultaneous oscillation in continuous wave at 1062 and 1337 nm in a Nd 3+ :YAl 3 (BO 3 ) 4 nonlinear crystal associated to the infrared laser channels 4 F 3/2 → 4 I 11/2 and 4 F 3/2 → 4 I 13/2 of Nd 3+ . Generation of yellow laser light at 592 nm produced by Type I self-sum-frequency-mixing of both fundamental infrared laser waves is observed under non-optimal phase matching conditions.
Semiconductor @ sensitizer composites for enhanced photoinduced processes
2021
Abstract This Chapter provides an overview of common procedures used for the preparation, characterization, and exploration of photocatalytic properties of composite materials based on inorganic semiconductors in combination with sensitizers, such as porphyrins, phthalocyanines, and related macrocyclic compounds as promoters of photoinduced processes. In this context the advantage of hybrid photocatalysts, obtained by impregnation of photosensitizers onto the surface of different semiconductors, designed for improving a choice of diverse reactions has been demonstrated, highlighting innovative aspects that contribute to better sustainability of the photocatalytic processes. Mechanistic deta…
Improved active fiber-based retroreflector with intensity stabilization and a polarization monitor for the near UV.
2021
We present an improved active fiber-based retroreflector (AFR) providing high-quality wavefront-retracing anti-parallel laser beams in the near UV. We use our improved AFR for first-order Doppler-shift suppression in precision spectroscopy of atomic hydrogen, but our setup can be adapted to other applications where wavefront-retracing beams with defined laser polarization are important. We demonstrate how weak aberrations produced by the fiber collimator may remain unobserved in the intensity of the collimated beam but limit the performance of the AFR. Our general results on characterizing these aberrations with a caustic measurement can be applied to any system where a collimated high-qual…
Numerical analysis of light soaking phenomenon in Ruthenium based Dye Sensitized Solar Cells
2017
Dye Sensitized Solar Cells (DSSCs) are widely considered one of the most promising third generation photovoltaic devices, especially thanks to their relatively low cost if compared to conventional solar cells. An interesting phenomenon affecting such devices is the so-called light soaking effect, consisting in the increase of cell main electrical parameters after the exposition to solar light. In this work, starting from the experimental characterization carried out on Ruthenium-based DSSCs, we report on a series of numerical analysis performed to better describe the above-mentioned light soaking effect in order to show the relationship between such phenomenon and the main physical paramete…