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81.
We propose a technique for rapid monitoring of single-mode operation of a tunable injection laser, based on analysis of the
fine structure of the power-current characteristic obtained with self-heterodyning, using a Michelson interferometer. The
technique makes it possible to determine the range for single-mode lasing and mode tuning as well as the presence of spurious
optical feedback, and to estimate the coherence length.
__________
Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 73, No. 1, pp. 119–123, January–February, 2006. 相似文献
82.
A major obstacle in realizing fast packet switching in all-optical networks is the large tuning delays of tunable optical devices. This article proposes a multiaccess scheme for all-optical local area networks that employs both wavelength and code concurrency. In this scheme, several users share a wavelength channel through code multiplexing. The delay performance of hybrid wavelength/code division multiaccess is obtained under a simple, suboptimal access protocol based on cyclic search. Due to the reduction in the number of wavelength channels without an associated reduction in transmission concurrency, hybrid multiaccess is robust against tuning delays. At a given network throughput, the hybrid scheme achieves considerably lower delays than that of Wavelength Division Multiple Access even with a small amount of code concurrency. Conversely, the hybrid network can support a higher load when there is a maximum allowable value for the average packet delay. 相似文献
83.
We describe a tunable diode laser spectrometer for the in situ simultaneous detection of the nitric acid and the water vapour by means of high resolution absorption spectroscopy on rovibronic lines, using a single laser emitting in the mid-infrared (5.8 μm) and a multipass cell. The instrument was designed to be installed on a high altitude aircraft, as a part of a composite payload for atmospheric aerosol studies. The instrument design criteria are discussed and the expected performances are compared with results of laboratory and field operation. Due to the high chemical activity of HNO3, that makes difficult to use a reference cell, a fast sweep detection of direct absorption was used for the measurement. An absorption sensitivity of about 2×10−4 was achieved with an integration time of 2.5 s, corresponding to a concentration of about 4 ppb of HNO3 in the cell and 0.1 ppb in the external aerosol. The data acquisition and processing techniques, based on the full molecular lineshape fitting are also shown and discussed, including some examples of the data acquired during the scientific flights. 相似文献
84.
Vetrichelvan M Valiyaveettil S 《Chemistry (Weinheim an der Bergstrasse, Germany)》2005,11(20):5889-5898
We report on the synthesis and characterization of a series of asymmetrically functionalized amphiphilic polymers with alternating pi-donor units (e.g., substituted benzene) and pi-acceptor units (e.g., pyridine) along the polymer backbone. The purpose of our present work involves incorporation of functional groups along the main chain to form intrachain hydrogen bonds, which promote planarization of the polymer backbone, and to fine-tune the optical properties. The structure-property relationship of polymers P1-P6 was investigated by means of analytical methods, such as FTIR spectroscopy, 1H and 13C NMR spectroscopy, UV/Vis spectroscopy, fluorescence spectroscopy, gel permeation chromatography, thermogravimetric analysis, cyclic voltammetry, and X-ray powder diffraction. All polymers were soluble in common organic solvents, and the optical and fluorescence spectra of the polymers showed significant changes according to the formation (P4, P5) or absence (P6) of intramolecular hydrogen bonding along the polymer backbone. Moreover, the 2,6- or 3,5-linkage of the pyridine rings in P5 and P6, respectively, reduced the conjugation along the polymer backbone and this is reflected in their optical properties. The optical properties of the polymers were influenced by the addition of acid (P1-P6), base (P4-P6), and metal ions (e.g., Cu2+, Fe3+, Ag+, Ni2+, Pd2+, Mn2+, Zn2+, Mg2+, and Pr3+). Such polymers could be used in various applications, including sensors and stimuli-responsive displays. 相似文献
85.
86.
制备了一种有机垂直光发射晶体管, 兼具有机发光二极管的发光和晶体管的开关调节两个功能.其结构为一个有机发光单元垂直堆叠在一个电容单元上,两单元通过一个共有的源电极连在一起.当电容单元被充电时,积累在源电极的电荷能有效地调节源极与有机层之间的载流子注入势垒,从而达到控制源漏输出电流的大小,最终控制发光单元发光的强度.实验结果表明,器件可提供02 mA的输出电流,其大小可驱动发光单元发光,工作电压(开启电压)为6 V.这种垂直集成方案,实现了器件多功能化,为有机发光二极管有源矩阵驱动的实际应用提供了一种新的解决方法.
关键词:
有机光发射晶体管
垂直
电容 相似文献
87.
We present an overview of recent developments in the fabrication and uses of colloidal crystals (CCs) for photonics and laser applications. Microparticles with a diameter in the range from 10 nm to 10 μm often have an intrinsic capability to spontaneously organize themselves from a colloidal suspension into 3D lattice structures. Such highly ordered 3D architectures of microparticles are called colloidal crystals (CCs). The CC structures have received tremendous attention as one of the facile and high‐throughput fabrication techniques of photonic crystals (PCs). We introduce here interesting precedents not only of diverse techniques of high‐quality CC structures, but also of their versatile applications in optical sensors responding to various external stimuli. This review also highlights a new potential use of the CCs as low‐threshold laser devices. We believe that a wide variety of CC architectures will play leading roles in the next generation of optoelectronic devices. 相似文献
88.
One-dimensional nanostructured manganese dioxide/polypyrrole (MnO2/PPy) composite was prepared by in situ chemical oxidation polymerization of pyrrole in the host of inorganic matrix of MnO2, using complex of methyl orange (MO)/FeCl3 as a reactive self-degraded soft-template. The morphology and structure of the composite were characterized by infrared spectroscopy (IR) X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The results show that the MnO2/PPy composite consists of α-MnO2 and PPy with nanotube-like structure. Electrochemical properties of the composite demonstrated the material showed good electrochemical reversibility after 500 charge-discharge cycles in the potential range of −0.4 to 0.6 V, the tube-like nanocomposite has the potential application in electrochemical capacitor. 相似文献
89.
90.
Guido Maione Antonio Punzi 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2013,19(3):277-299
In recent years, several research works proposed fractional-order controllers as means to improve the performances of common proportional, integral and derivative controllers. However, the design and tuning methods for these new controllers are still at their infancy. As a contribute for filling this gap, this article proposes a two-step design approach. First, differential evolution determines the fractional integral and derivative actions satisfying the required time-domain performance specifications. Second, particle swarm optimization determines rational approximations of the irrational fractional operators as low-order, stable, minimum-phase transfer functions with poles interlacing zeros. Extensive time- and frequency-domain simulations validate the efficiency of the proposed approach. 相似文献