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991.
A novel bend-insensitive long-period fiber grating (LPFG) sensor written using focused CO2 laser pulses is demonstrated, for the first time, to our knowledge. It is found that the central wavelength shift of such a LPFG is only −0.018 nm even for a curvature of 1.1 m−1 at the most bend-insensitive position of the LPFG. Experimental results show that the bend sensitivity of the central wavelength of the LPFG has a periodic distribution along its circular directions. Such a bend-insensitive sensor could be used to solve the problem of cross-sensitivity between bend and other measurands, such as temperature, strain or refractive index, which is an unsolved problem for LPFG sensors in practice. In addition, the bend sensitivity of the LPFG can be adjusted by selecting its circular positions. 相似文献
992.
993.
Pr2O3,Sm2O3,Eu2O3及Dy2O3掺杂SrTiO3的发光光谱 总被引:2,自引:2,他引:0
SrTiO_3粉末分别用Pr_2O3、Sm_2O_3、Eu_2O_3以及Dy_2O_3掺杂处理后,以SrTiO_3能吸收的光波(≤387nm)激发后发出的荧光具有稀土离子的发光特征。 相似文献
994.
YAN Minhui CHEN Jianping LI Jianlang JINAG Wenning CHEN Junfeng LI Xin 《Chinese Journal of Lasers》2002,11(3):219-222
1 Introduction GrowingcommunicationtrafficdemandsmorewavelengthstobeusedinopticalDWDM(densewavelengthdivisionmultiplexing )systemsandnetworks.OpticalfiberRamanamplifierwithitswideamplificationbandwidthandflexiblecenterwavelengthisthepromisingcandidate[… 相似文献
995.
Background correction by wavelength modulation using a microcomputer in atomic emission spectrometry
Ali Gökmen Mehrdad Delzendeh Mürvet Volkan O. Yavuz Ataman John M. Ottaway 《Mikrochimica acta》1986,89(1-6):357-367
An Apple IIe microcomputer was employed to correct the background radiation in electrothermal atomization atomic emission spectrometry (ETA-AES). In ETA-AES, black-body radiation from the atomizer as well as any broadband molecular emission should be corrected to obtain an atomic signal alone. A quartz plate run by a G325D galvanometric motor was placed before the exit slit of a 256 mm Littrow monochromator. Improvements by a novel pulsed 3-step square waveform are demonstrated compared with the ordinatry 3-step square waveform. A soft delay was also applied in order to avoid taking data at transition stages of the quartz plate. A line and a continuum source are used to simulate offsetting of the DC component of the signal prior to the ADC. This provides a better utilization of the full dynamic range of the converter. 相似文献
996.
The usable non-repetitive measuring range of birefringent fibre-optic based sensors is increased by wavelength multiplexing and demultiplexing. The theory involved along with experiments demonstrating the principle are discussed. 相似文献
997.
Hans J. Liebe 《International Journal of Infrared and Millimeter Waves》1984,5(2):207-227
Absolute attenuation rates due to water vapor and moist nitrogen have been measured in the laboratory at 138 GHz, 282 and 300 K, pressures up to 1.5 atm, and relative humidities from 80 to 100 percent. The computer-controlled measuring system is comprised of a millimeter wave resonance spectrometer (0.15 km effective path length) and a humidity simulator. Several shortcomings of earlier measurement attempts have been rectified. The data are interpreted as a water vapor continuum spectrum consisting of two terms, namely strong self-broadening (H2O–H2O) plus foreign-gas-broadening (H2O–N2) contributions. Implications of the new results for modeling atmospheric EHF window transparencies and for revising established H2O line broadening theory are discussed.The work was supported in part by the U.S. Army Research Office under Contract AR0 101-83. 相似文献
998.
The dark electrical characteristic of n+ on p long wavelength Hg1−xCdxTe photovoltaic detectors has been studied as a function of applied bias voltages. The diodes under study were given different surface treatments prior to their passivation. The dark current components have been identified using the already known carrier transport mechanisms across the junction. It is reported that the diodes under investigation have an excess leakage current component that exhibits quadratic dependence on the applied reverse bias voltage across the diode. The origin of this excess current is found to be closely associated with the ohmic currents. The diodes with higher ohmic current exhibit higher excess leakage current. 相似文献
999.
1000.
H. Akabli A. Almaggoussi A. Abounadi A. Rajira K. Berland T.G. Andersson 《Superlattices and Microstructures》2012
We have studied the conduction band profile and the intersubband transition energy, E12, of Al1−yInyN/Ga1−xInxN quantum well structures. We have considered how material parameters such as non-parabolicity and the uncertainty in the bowing parameter affect E12 and the corresponding wavelength, λ12. The calculations include strain and cover the transition range from telecommunication wavelengths (1.55 μm) to the mid-infrared (∼ 10 μm). 相似文献