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Test of Various Photocathodes  [PDF]
Ryoji Enomoto,Takayuki Sumiyoshi,Yoshio Fujita
Physics , 1994, DOI: 10.1016/0168-9002(94)90540-1
Abstract: A test of various photocathodes was carried out. The tested materials were CsI, CsTe, their multi-layers and so on. The quantum efficiencies of the various materials were measured under a vacuum and/or after exposure to several kinds of gases.
Ion-induced effects in GEM & GEM/MHSP gaseous photomultipliers for the UV and the visible spectral range  [PDF]
A. Breskin,D. Mormann,A. Lyashenko,R. Chechik,F. D. Amaro,J. M. Maia,J. F. C. A. Veloso,J. M. F. dos Santos
Physics , 2005, DOI: 10.1016/j.nima.2005.08.005
Abstract: We report on the progress in the study of cascaded GEM and GEM/MHSP gas avalanche photomultipliers operating at atmospheric pressure, with CsI and bialkali photocathodes. They have single-photon sensitivity, ns time resolution and good localization properties. We summarize operational aspects and results, with the highlight of a high-gain stable gated operation of a visible-light device. Of particular importance are the results of a recent ion-backflow reduction study in different cascaded multipliers, affecting the detector's stability and the photocathode's liftime. We report on the significant progress in ion-blocking and provide first results on bialkali-photocathode aging under gas multiplication.
A Study on Spectral Response Characterization of Super S25 photocathodes
Super S25与New S25光电阴极的光谱响应特性的数值模拟

光子学报 , 2004,
Abstract: According to the spectral response formula of multialkali photocathode ,a simulation of the spectral response for Super S25 and New S25 photocathodes are carried out. Some characteristic parameters are obtained .The internal mechanism of good properties of Super S25 and New S25 photocathodes and some technical methods which could be probablely used in three photocathodes production are discussed through analyzing the results of the simulation.
The optical properties of gold
Otto Loebich
Gold Bulletin , 1972, DOI: 10.1007/BF03215148
Abstract: The characteristic optical properties of gold, combined with its complete resistance to attack in any surroundings and its ability to be applied as very thin films, have led to a number of interesting and diverse applications in industry. The author, formerly Research Manager to the Metals Department of DEGUSSA, reviews these uses and the special properties upon which they are based.
Optical Properties of the Coupling Interface for Planar Optical Waveguides  [PDF]
Yu Zheng, Ji-An Duan
Optics and Photonics Journal (OPJ) , 2011, DOI: 10.4236/opj.2011.13018
Abstract: Planar optical waveguides are the key elements in a modern, high-speed optical network. An important problem facing the optical fiber communication system, specifically planar optical waveguides, is coupling. The current study presents a coupling model for planar optical waveguides and optical fibers. The various effects of the optical properties of the coupling interface were analyzed by the scalar finite difference beam propagation method, including the thickness, with or without the matching refractive index of the interface adhesive. The findings can serve as a guide for planar optical waveguide packaging.
Optical properties of graphene  [PDF]
L. A. Falkovsky
Physics , 2008, DOI: 10.1088/1742-6596/129/1/012004
Abstract: Reflectance and transmittance of graphene in the optical region are analyzed as a function of frequency, temperature, and carrier density. We show that the optical graphene properties are determined by the direct interband electron transitions. The real part of the dynamic conductivity in doped graphene at low temperatures takes the universal constant value, whereas the imaginary part is logarithmically divergent at the threshold of interband transitions.
Optical properties of BiTeBr and BiTeCl  [PDF]
A. Akrap,J. Teyssier,A. Magrez,P. Bugnon,H. Berger,A. B. Kuzmenko,D. van der Marel
Physics , 2014, DOI: 10.1103/PhysRevB.90.035201
Abstract: We present a comparative study of the optical properties - reflectance, transmission and optical conductivity - and Raman spectra of two layered bismuth-tellurohalides BiTeBr and BiTeCl at 300 K and 5 K, for light polarized in the a-b planes. Despite different space groups, the optical properties of the two compounds are very similar. Both materials are doped semiconductors, with the absorption edge above the optical gap which is lower in BiTeBr (0.62 eV) than in BiTeCl (0.77 eV). The same Rashba splitting is observed in the two materials. A non-Drude free carrier contribution in the optical conductivity, as well as three Raman and two infrared phonon modes, are observed in each compound. There is a dramatic difference in the highest infrared phonon intensity for the two compounds, and a difference in the doping levels. Aspects of the strong electron-phonon interaction are identified. Several interband transitions are assigned, among them the low-lying absorption $\beta$ which has the same value 0.25 eV in both compounds, and is caused by the Rashba spin splitting of the conduction band. An additional weak transition is found in BiTeCl, caused by the lower crystal symmetry.
Optical properties of unconventional superconductors  [PDF]
Takashi Yanagisawa,Hajime Shibata
Physics , 2004,
Abstract: The optical conductivity measurements give a powerful tool to investigate the nature of the superconducting gap for conventional and unconventional superconductors. In this article, first, general analyses of the optical conductivity are given stemmed from the Mattis-Bardeen formula for conventional BCS superconductors to unconventional anisotropic superconductors. Second, we discuss the reflectance-transmittance (R-T) method which has been proposed to measure far-infrared spectroscopy. The R-T method provides us precise measurements of the frequency-dependent conductivity. Third, the optical conductivity spectra of the electron-doped cuprate superconductor Nd_{2-x}Ce_xCuO_4 are investigated based on the anisotropic pairing model. It is shown that the behavior of optical conductivity is consistent with an anisotropic gap and is well explained by the formula for d-wave pairing in the far-infrared region. The optical properties of the multiband superconductor MgB_2, i n which the existence of superconductivity with relatively high-T_c (39K) was recently announced, is also examined to determine the symmetry of superconducting gaps.
Electronic and optical properties in graphane  [PDF]
M. H. Lee,H. C. Chung,J. M. Lu,C. P. Chang,M. F. Lin
Physics , 2014,
Abstract: We develop the tight-binding model to study electronic and optical properties of graphane. The strong sp3 chemical bondings among the carbon and hydrogen atoms induce a special band structure and thus lead to the rich optical excitations. The absorption spectrum hardly depends on the direction of electric polarization. It ex- hibits a lot of shoulder structures and absorption peaks, which arise from the extreme points and the saddle points of the parabolic bands, respectively. The threshold op- tical excitations, only associated with the 2px and 2py orbitals of the carbon atoms, are revealed in a shoulder structure at ?3.5 eV. The ?rst symmetric absorption peak, appearing at ~11 eV, corresponds to energy bands due to the considerable hybridiza- tion of carbon 2pz orbitals and H 1s orbitals. Also, some absorption peaks at higher frequencies indicate the bonding of 2s and 1s orbitals. These results are in sharp contrast to those of the sp2 graphene systems.
Optical microvariability properties of BALQSOs  [PDF]
Ravi Joshi,Hum Chand,Alok C. Gupta,Paul J. Wiita
Physics , 2010, DOI: 10.1111/j.1365-2966.2010.18099.x
Abstract: We present optical light curves of 19 radio quiet (RQ) broad absorption line (BAL) QSOs and study their rapid variability characteristics. Systematic CCD observations, aided by a careful data analysis procedure, have allowed us to clearly detect any such microvariability exceeding 0.01--0.02 mag. Our observations cover a total of 13 nights (~72 hours) with each quasar monitored for about 4 hours on a given night. Our sample size is a factor of three larger than the number of radio-quiet BALQSOs previously searched for microvariability. We introduce a scaled F-test statistic for evaluating the presence of optical microvariability and demonstrate why it is generally preferable to the statistics usually employed for this purpose. Considering only unambiguous detections of microvariability we find that ~11 per cent of radio-quiet BALQSOs (two out of 19 sources) show microvariability for an individual observation length of about 4 hr. This new duty cycle of 11 per cent is similar to the usual low microvariability fraction of normal RQQSOs with observation lengths similar to those of ours. This result provides support for models where radio-quiet BALQSO do not appear to be a special case of the RQQSOs in terms of their microvariability properties.
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