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Modulated optical reflectance (MOR) technique of laser photothermal analysis is implemented to magnetoresistive La0,7Sr0,3MnO3 (LSMO) thin film. The sensor signal is based on the measurement of the variations of optical reflectivity of the sample subjected to periodic photothermal modulation. Assuming Drude model, it is proportional to the variations of the charge carrier concentration. The optical setup is mounted as a flexible laser microscope, based on elements of integral and fibre optics. The noncontact, nondestructive measurement scheme is prospective for applications to structural analysis and characterization of new magnetic and magnetoelectric materials for the next generation electronic devices. [ABSTRACT FROM AUTHOR]

Pulsed capillary discharge is a compact device that is used to perform fast electrical discharge that is used to produce transient plasma. In this work, a more economical imaging technique is developed in order to study the dynamics of the plasma that is formed in a capillary tube. The imaging system consists of two main devices, a four-frame gated micro-channel plate and a Nikon Coolpix5000 camera. The time-resolved imaging that we have performed in order to study the dynamics of the plasma that is formed in a 10 mm long and 1 mm diameter low pressure capillary tube is reported. The images obtained portrayed that the plasma is heated up when the magnitude of the current is around the maximum and cools down when the current magnitude is around the minimum. [ABSTRACT FROM AUTHOR]

Bismuth borate glass is of great interest in optoelectronic devices due to its low melting temperature (600–800 °C), extensive glass formation range, high refractive index ranging from 1.9 to 2.3, high physical and chemical stability, and nonlinear optical property. A systematic bismuth borate glass series in the systems of (Bi2O3)x-(B2O3)1-x have been successfully prepared by melt quenching technique over a wide range of composition (x = 35–70 mol%). Their elastic properties have been measured from their densities as well as longitudinal (VL) and shear ultrasonic wave velocities (Vs) which have been determined at room temperature by the MBS8000 Ultrasonic Data Acquisition system at a frequency of 5 MHz. The variation of ultrasonic wave velocities and elastic modulus such as longitudinal, Young's, bulk and shear modulus, Poisson's ratio, and micro hardness are discussed with respect of the Bi2O3 content. [ABSTRACT FROM AUTHOR]

We examine some aspects of the continuous photodetection model for photocounting processes in cavities. We work out a microscopic model that describes the field-detector interaction and deduce a general expression for the Quantum Jump Superoperator (QJS), that shapes the detector's post-action on the field upon a detection. We show that in particular cases our model recovers the QJSs previously proposed ad hoc in the literature and point out that by adjusting the detector parameters one can engineer QJSs. [ABSTRACT FROM AUTHOR]

Analyzes generates by Scanning Electronic Microscopy (SEM/BSE), Fourier Transform Infrared Spectroscopy (FTIR) and X-Ray Diffraction (XRD) were used in order to compare epitaxial layers of PbSnTe, grown high quality crystalline by Hot Wall Beam Epitaxy—HWBE technique, directly over single crystal BaF2 wafers, p type. The PbSnTe/BaF2 heterostructures were analyzed electrically by Hall Effect (HE), in electrical contacts in the PbSnTe layers (Van der Pauw method), and optoeletronic by Detectivity (D), are used as thermal infrared detectors that work with the wavelength—3 μm<λ<14 μm at 77 K temperature. [ABSTRACT FROM AUTHOR]

We report on the performance (watt-level red output at ∼657 nm, long-term passive single-frequency operation and wavelength tuning over ∼4 nm) of an all solid-state continuous-wave Nd:YLiF4 (Nd:YLF) ring laser operating on the 4F3/2–4l13/2 σ-polarized transition (λω = 1314 nm) and intra-cavity frequency-doubled by a temperature-tuned periodically-poled KTiOPO4 (ppKTP) crystal. Evidence of self-mode-locking via cascading second-order nonlinearities is observed when the ppKTP is strongly phase-mismatched on the Kerr-lens focusing nonlinearity side. This red laser source is well suited for calcium and silver atom spectroscopy and cooling. [ABSTRACT FROM AUTHOR]

This paper deals with the use of micro-plasma noise for solar cells diagnostic purposes. When a high electric field is applied to a PN junction containing some technological imperfections, enhanced impact ionization arises in micro-sized regions, thus producing so-called micro-plasmas, which in turn can lead to the deterioration in quality or destruction of the PN junction. It is therefore advisable to use methods which can indicate the presence of micro-plasma in the junction and make the quality assessment and quantitative description of the tested cells possible. © 2007 American Institute of Physics [ABSTRACT FROM AUTHOR]

The low frequency noise of optoelectronic coupled devices (OCDs) was measured in the system designed and constructed by the authors. The RTS noise was observed in some devices. The analysis of RTS noise in time and frequency domains is presented. The values of fRTS were found from spectrum and from observed RTS noise on the base of tup and tdown evaluation. The results of evaluations were compared. The dependencies of tup, tdown and fRTS on values of Id were described. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

The most advanced microscopic treatments of optoelectronic quantum devices are reviewed, with special emphasis on the design and simulation of novel quantum-cascade devices operating in the Terahertz spectral region. After recalling the fundamentals of hot-electron transport versus nonequilibrium energy-relaxation and carrier-redistribution in such devices, a few simulated experiments are presented and discussed. © 2005 American Institute of Physics [ABSTRACT FROM AUTHOR]

Pulsed lasers are convenient generators of shocks in materials. The efficacy of laser shock generation depends on several factors including laser-target coupling, laser pulse temporal shape and intensity, and the resultant pressure profile generated at the target surface. Target coupling is a dynamic mechanism that changes as the target surface evolves due to heating, ionization and ablation during laser irradiation. Confining a metal target surface using a transparent “tamper” material can increase the impulse transferred to the target, but also can cause decoupling of the laser energy from the target as the heated tamper begins to move the laser absorption region away from the metal surface. We have analyzed this process using the radiation hydrodynamics code Lasnex in an attempt to simulate experiments using planar targets and determine the coupling efficiency versus tamper material properties. Good agreement with experimental measurements of the shock pressure in Al and PMMA were obtain using laser absorption values of 40%. Dielectric tamping of the laser absorption increased the shock pressures by factors of 2 to 3. Further increases in pressure into the megabar regime were obtained inside the tamping dielectric as a radiatively-coupled ionization wave propagated back toward the laser. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

Synchrotron radiation-excited etching of compound semiconductor, ZnTe, was investigated using the SF6 and Ar gases. In the case of SF6 gas, the ZnTe was not etched but thin film of a fluorine containing material, e.g. ZnF2, was deposited on the surface of ZnTe. On the other hand, ZnTe was etched by using Ar gas under the negative sample bias to the sample. The etched pattern obtained by placing a Ni mesh showed that only the irradiated area was etched. The etching rate was estimated to be around 4.5×10-2 Å/mA·min. © 2004 American Institute of Physics [ABSTRACT FROM AUTHOR]

We report THz generation based on two systems: 1) continuous-wave (cw) laser generation in molecular gas lasers, and 2) short pulse generation in photoconductive antennas, gated by femtosecond near-infrared Ti:sapphire lasers. With the first system, we have generated tens of monochromatic cw laser lines over the last years, extending roughly from 40 microns to several hundred microns. This is done by optical pumping of gas lasers based on polar molecules such as methanol and its isotopes. In the second system, under development, pulsed THz radiation is generated by a photoconductive antenna built in a semi-insulating GaAs substrate excited by femtosecond pulses from a near-infrared (800 nm) Ti:sapphire laser. [ABSTRACT FROM AUTHOR]

The Multi Pixel Photon Counter (MPPC) or Silicon Photomultiplier (SiPM) consists of an array of Geiger-mode photodiodes (microcells). It is a promising device for PET thanks to its high photon detection efficiency (PDE) and immunity to high magnetic fields. It is also very easy to use, with simple electronic read-out, high gain and small size. In this work we evaluate the performance of three 1×1 mm2 SiPM and one 2×2 SiPMs array (6×6 mm2 of active area). We examine the dependence of the energy resolution and the gain of these devices on the temperature and reverse bias when coupled to MLS and LYSO scintillator crystals. The good performance of these devices up to 7 Tesla has been also confirmed. [ABSTRACT FROM AUTHOR]

In this work, we exploit the synchrotron X-ray Renninger scanning to inspect in-plane strain introduced in the capping process of InAs/GaAs (001) quantum dots as a function of their growth rates. [ABSTRACT FROM AUTHOR]

Diluted magnetic semiconductor (DMS) materials have attracted much attention because of the interest in both investigations of fundamental physical properties and promising applications for various spintronic devices. Among many DMS structures, (III1-xMnx)V ferromagnetic semiconductor quantum structures have been particularly attractive due to their potential applications in spintronic devices and they have combined properties of both III–V semiconductors and Mn ferromagnetic compounds, and the excellent advantages derived by utilizing mature III–V based heterostructure technology. Even though not many papers have been reported on the formation of one layer of (III1-xMnx)V Quantum structure-Quantum Dots(QDs) and Quantum Wires(Q-Wire), systematic studies concerning microstructural, magnetic, and optical properties of the (III1-xMnx)V quantum structure have been more attractive because of the interest in promising applications in optoelectronic devices, such as spin injection lasers and spin switching devices. [ABSTRACT FROM AUTHOR]

We describe the fabrication and operation of quantum cascade ring lasers providing grating-coupled surface emission. The devices exhibit tunable far fields, ranging from spot- to ring-shaped symmetric beam cross sections, depending on the grating period. This—along with threshold current densities as low as for comparable Fabry-Perot lasers - demonstrates the compatibility of reduced beam divergence and two-dimensional integrability, resulting in an attractive light source for spectroscopic applications. [ABSTRACT FROM AUTHOR]

Zinc oxide (ZnO) is a promising candidate for short-wavelength optoelectronic devices. Due to the lack of stability and reproducibility of p-type ZnO, ZnO heterojunction devices are of considerable interest. In this work, the performance of ZnO nanorod/NiO light emitting diodes (LEDs) was investigated. Both materials were fabricated using inexpensive solution based process. Due to the low fabrication temperature, ZnO nanorods contained considerable concentration of point defects. Post-fabrication treatments could significantly change ZnO nanorod properties. The effect of post-fabrication annealing on ZnO properties and device performance were discussed. [ABSTRACT FROM AUTHOR]