328,193 research outputs found
Long period grating for 3-5 mu m quantum-well infra-red photodetectors
No full textBy considering all possible high order diffracted waves, the authors calculate the coupling efficiency of long period gratings for 3-5 mu m quantum-well infra-red photodetectors (QWIPs) on the basis of the modal expansion model (MEM). A large coupling efficiency for 3-5 mu m QWIPs has been demonstrated. This greatly reduces the difficulties in fabricating 3-5 mu m grating coupled QWIPs and opens the way to fabricate high performance 3-5 mu m and two colour QWIPs image arrays
Ligand-Specific Regulation of the Endogenous Mu-Opioid Receptor by Chronic Treatment with Mu-Opioid Peptide Agonist
No full textSince the discovery of the endomorphins (EM), the postulated endogenous peptide agonists of the mu-opioid receptors, several analogues have been synthesized to improve their binding and pharmacological profiles. We have shown previously that a new analogue, cis-1S,2R-aminocyclohexanecarboxylic acid2-endomorphin-2 (ACHC-EM2), had elevated mu-receptor affinity, selectivity, and proteolytic stability over the parent compound. In the present work, we have studied its antinociceptive effects and receptor regulatory processes. ACHC-EM2 displayed a somewhat higher (60%) acute antinociceptive response than the parent peptide, EM2 (45%), which peaked at 10 min after intracerebroventricular (icv) administration in the rat tail-flick test. Analgesic tolerance developed to the antinociceptive effect of ACHC-EM2 upon its repeated icv injection that was complete by a 10-day treatment. This was accompanied by attenuated coupling of mu-sites to G-proteins in subcellular fractions of rat brain. Also, the density of mu-receptors was upregulated by about 40% in the light membrane fraction, with no detectable changes in surface binding. Distinct receptor regulatory processes were noted in subcellular fractions of rat brains made tolerant by the prototypic full mu-agonist peptide, DAMGO, and its chloromethyl ketone derivative, DAMCK. These results are discussed in light of the recently discovered phenomenon, that is, the “so-called biased agonism” or “functional selectivity
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Laser-light-absorption studies at 1. 06. mu. m, 0. 53. mu. m, and 0. 35. mu. m wavelengths
No full textResults are presented of light absorption in a series of wavelength scaling experiments recently completed at LLNL. The Argus facility was used to do target studies at 1.06..mu..m, 0.53..mu..m and 0.35..mu..m. Box calorimeter scattered light measurements implied greatly improved laser light absorption for both high Z and low Z plasmas at laser wavelengths shorter than 1.06..mu..m. Furthermore, at the 0.35..mu..m laser wavelength, the inferred absorption is nearly 100% over a substantial range of incident laser intensities. Our results further show a dramatic decrease in the stimulated Brillouin scattered light at 0.35..mu..m relative to the values at 1.06..mu..m and 0.53..mu..m
Influence of growth parameters of frequency-radio plasma nitrogen source on extending emission wavelengths from 1.31 mu m to 1.55 mu m GaInNAs/GaAs quantum wells grown by molecular-beam epitaxy
No full textHigh (42.5%) indium content GaInNAs/GaAs quantum wells with room temperature emission wavelength from 1.3 mu m to 1.5 mu m range were successfully grown by Radio Frequency Plasma Nitrogen source assisted Molecular Beam Epitaxy. The growth parameters of plasma power and N-2 How rate were optimized systematically to improve the material quality. Photoluminescence and transmission electron microscopy measurements showed that the optical and crystal quality of the 1.54 mu m GaInNAs/GaAs QWs was kept as comparable as that in 1.31 mu m
Numerical study of strained InGaAs quantum well lasers emitting at 2.33 mu m using the eight-band model
No full textWe investigate the band structure of a compressively strained In(Ga)As/In(0.53)Ga(0.47)As quantum well (QW) on an InP substrate using the eight-band k.p theory. Aiming at the emission wavelength around 2.33 mu m, we discuss the influences of temperature, strain and well width on the band structure and on the emission wavelength of the QW. The wavelength increases with the increase of temperature, strain and well width. Furthermore, we design an InAs/In(0.53)Ga(0.47)As QW with a well width of 4.1 nm emitting at 2.33 mu m by optimizing the strain and the well width
EXPTIME Tableaux for the Coalgebraic Mu-Calculus
No full textThe coalgebraic approach to modal logic provides a uniform framework that captures the semantics of a large class of structurally different modal logics, including e.g. graded and probabilistic modal logics and coalition logic. In this paper, we introduce the coalgebraic mu-calculus, an extension of the general (coalgebraic) framework with fixpoint operators. Our main results are completeness of the associated tableau calculus and EXPTIME decidability. Technically, this is achieved by reducing satisfiability to the existence of non-wellfounded tableaux, which is in turn equivalent to the existence of winning strategies in parity games. Our results are parametric in the underlying class of models and yield, as concrete applications, previously unknown complexity bounds for the probabilistic mu-calculus and for an extension of coalition logic with fixpoints
1.55-mu m resonant cavity enhanced photodiode based on MBE grown Ge quantum dots
No full textSelf-assembly Ge quantum dots (QD) on Si and Si/Ge mutli-quantum-wells (MQW) are grown by MBE. The island size and island density was investigated by atomics force microscopy. Ten-layer and twenty-layer MQW were selected for photodiode device fabrication. In photoluminescence (PL), a broad peak around 1.55-mu m wavelength was observed with higher peak intensity for the 10-layer MQW which had less defects than the 20-layer sample. Resonant cavity enhanced (RCE) photodiodes were fabricated by bonding on a SOI wafer. Selected responsivity at 1.55 mu m was successfully demonstrated. (c) 2005 Elsevier B.V. All rights reserved
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ARGUS disk-target experiments at 1. 06. mu. m, 0. 53. mu. m, 0. 35. mu. m
No full textWe report on ARGUS wavelength scaling experiments on disk targets at 1.06 ..mu..m, 0.53 ..mu..m, and 0.35 ..mu..m. Measurements were made of absorption, stimulated Brillouin and Raman scattering, and 3/2 harmonic light
1.58 mu m InGaAs quantum well laser on GaAs
No full textWe demonstrate the 1.58 mu m emission at room temperature from a metamorphic In0.6Ga0.4As quantum well laser grown on GaAs by molecular beam epitaxy. The large lattice mismatch was accommodated through growth of a linearly graded buffer layer to create a high quality virtual In0.32Ga0.68As substrate. Careful growth optimization ensured good optical and structural qualities. For a 1250x50 mu m(2) broad area laser, a minimum threshold current density of 490 A/cm(2) was achieved under pulsed operation. This result indicates that metamorphic InGaAs quantum wells can be an alternative approach for 1.55 mu m GaAs-based lasers. (C) 2007 American Institute of Physics
Passive Q-switching in a diode-side-pumped Nd:YAG laser at 1.319 mu m
No full textWe demonstrated a passively Q-switched Nd:YAG laser operating at 1.319 mu m using a transmission-type single-wall carbon nanotube (SWCNT) as the saturable absorber. This is the first report on using SWCNT as a Q-switcher for 1.319 mu m Nd:YAG laser in a side-pumped configuration. A maximum output power of 780 mW was obtained with 1.15-mu s pulse duration and 42.7-kHz repetition rate. (C) 2013 Society of Photo-Optical Instrumentation Engineers (SPIE
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