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排序方式: 共有115条查询结果,搜索用时 15 毫秒
1.
M.Yu. Tretyakov V.V. Parshin M.A. Koshelev A.P. Shkaev A.F. Krupnov 《Journal of Molecular Spectroscopy》2006,238(1):91-97
Extension of the working frequency of modern resonator spectrometers into submillimeter wave range is described. Experimental record of atmospheric absorption spectrum covering 45-370 GHz range is demonstrated for the first time, and measured water vapor J′ka′, kc′-Jka, kc = 51,5-42,2 at 325 GHz line parameters are presented. For the first time pressure lineshift for the 325-GHz water vapor line is measured. Further extension of working range is discussed. New estimations of physical limits of time needed for measurements of absorption in the whole Backward Wave Oscillator (BWO) range are given for phase continuous synthesizer regime. Basic schemes of fast broadband continuous phase synthesized sources are discussed. Verification of the previous measurements of water vapor 31,3-22,0 at 183 GHz line parameters is presented. Comparisons with ringdown resonator spectrometers are given. 相似文献
2.
G. K. Vlasov D. N. Vylegzhanin N. A. Dolgikh E. I. Chizhikoya 《International Journal of Infrared and Millimeter Waves》1995,16(1):33-73
The possibility of the IR-radiation detecting in crystals of direct-gap semiconductors, caused by effects of IR-quenching of probe visible-range radiation within the region of a crystal relative transparency, is studied both theoretically and experimentally. The comparison of some mechanisms investigated allows to conclude that the most probable explanation of the IR-quenching effect, experimentally observed in the CdS crystal, is the mechanism of probe radiation absorption with photon energy deficit with respect to exciton resonance, which is eliminated due to exchange interaction of a free exciton in the intermediate state with spherical excitons localized on manyelectron atoms of impurity. 相似文献
3.
G. K. Vlasov E. I. Chizhikova D. N. Vylegzhanin 《International Journal of Infrared and Millimeter Waves》1994,15(1):121-135
The theory of new type detectors based on the quenching of secondary emission in direct-gap semiconductors (lines of Raman light scattering due to interaction between free and bound excitons in the crystal, and also bands of edge radiation) caused by IR or submillimeter radiation is proposed. The results obtained are confirmed by the experiment performed for CdS crystal excited by ultraviolet radiation of mercury lamp, at liquid helium temperature. 相似文献
4.
P. Goy 《International Journal of Infrared and Millimeter Waves》1982,3(2):221-234
This paper describes experimental results obtained with a packaged GaAs Schottky barrier diode in contact with a coaxial connector and placed across waveguides for bands Ka, V, E, W or F. Among the microwave sources used for calibration were 9 carcinotrons in the frequency interval 51–490 GHz. As soon as the frequency F is above the waveguide cut-off frequency, the different characteristics do not depend critically on the waveguide size for V, E, W and F bands. The video detection sensitivity, of several 100 mV/mW at 50 GHz and below, decreases as F–4 in the range 51–500 GHz. Coupling an X-band centimeter frequency via the coaxial connector and a millimeter frequency via the waveguide permits harmonic mixing in the diode. Between 36 and 490 GHz, the harmonic mixing number varies from 3 up to the very large value 40 with conversion losses from 18 to 88 dB. The minimum detectable signal in the 100 kHz band can be as low as –90 dBm at 80 GHz. A noticeable millimeter power is available at the waveguide output from injected centimeter power by harmonic generation. Starting for instance with 100 mW around 11.5 GHz, we have measured 0.1 mW at 80 GHz and 0.1 W at 230 GHz. To illustrate the possibility of creating usable millimeter and submillimeter wave without heavy equipment (such as carcinotrons or millimeter klystron) we report spectroscopic experiments in Rydberg atoms. Resonances have been observed up to 340 GHz by harmonic generation (28th harmonic) from an X-band klystron). 相似文献
5.
研究了超短光脉冲在GaAs表面激发相干亚毫米波振幅随入射角变化的规律,前后向辐射比值随入射角度变化的规律,实验测量了GaAs表面镀上极薄金属薄膜后产生的相干亚毫米波振幅对薄膜厚度的依赖关系,利用光生载子偶极辐射的理论模型成功地解释了实验得到的角度依赖关系和相干亚毫米波的偏振特性。 相似文献
6.
A. H. F. van Vliet Th. de Graauw S. Lidholm H. van de Stadt 《International Journal of Infrared and Millimeter Waves》1982,3(6):817-823
A heterodyne receiver is described in which an InSb hot electron bolometer is used as a mixer. The local oscillator power is obtained by doubling the frequency of a backward wave oscillator. The receiver operates between 460 and 500 GHz (0.65–0.6 mm). Noise temperatures amount typically to 1000 K. 相似文献
7.
A review of physical principles of design as well as some ways of technical realization of controlled resonance semiconductor devices at millimeter and submillimeter wavelengths is presented. The operation of such devices is based on cyclotron and magnetoplasma resonances as well as on Fabry-Perot resonance. Such choice has been made due to the fact that these resonance phenomena are the most typical ones for the magnetized semiconductor plasma. 相似文献
8.
V. K. Kiseliov 《International Journal of Infrared and Millimeter Waves》2000,21(2):163-179
The paper considers an optimum sectional waveguide taper (OSWT) which at a shortest length of the transition region provides nearly adiabatic propagation of the fundamental mode between circular, widely different in diameter quasioptical transmission lines of class hollow dielectric waveguide (HDW). Derived as a consequence of coaxial circular-horn sections, the OSWT offers all the advantages of a simple geometry and lends itself to simple fabrication techniques. The relationships among the critical geometrical parameters and the loss calculation formulae are presented. The comparison studies show that even at a few sections, the OSWT is almost as good in performance as the parabolic taper, but the OSWT is much better from a mechanical viewpoint. And compared to the ordinary linear taper, the OSWT allows essential cut in length and loss with the broadbandness kept. The HDW-based four-sectional OSWT has been fabricated and tested in a quite broad wave range 2,5-8 mm. The testing results lend a good support to the analytical formulae lying at the basis of the design software. 相似文献
9.
J. P. Creen D. Vèron P. Belland 《International Journal of Infrared and Millimeter Waves》1986,7(11):1747-1767
The advantages of supported metal strip gratings with respect to free-standing metal meshes are pointed out for applications as laser output couplers. A new, simple formula for the power transmission through the strip grating on a dielectric plate is derived from a line equivalent-circuit model. This formula is in good agreement with measurements performed on several samples, at different submillimeter wavelengths. An application to output couplers of far-infrared gas discharge lasers allows to improve the reliability of such lasers.x Unité associée au CNRS. U.A. 836. 相似文献
10.
Morvan Salez Pascal Febvre William R. Mcgrath Bruce Bumble Henry G. Leduc 《International Journal of Infrared and Millimeter Waves》1994,15(2):349-368
A waveguide SIS heterodyne receiver using a Nb/AlOX/Nb junction has been built for astronomical observations of molecular transitions in the frequency range 600 GHz - 635 GHz, and has been successfully used at the Caltech Submillimeter Observatory (CSO). We report double sideband (DSB) receiver noise temperatures as low as 245 K at 600 GHz -610 GHz, and near 300 K over the rest of the bandwidth. These results confirm that SIS quasiparticle mixers work well at submillimeter-wave frequencies corresponding to photon energies of at least 90% of the superconductor energy gap. In addition, we have systematically investigated the effect on the receiver performance of the overlap between first-order and second-order photon steps of opposite sign at these frequencies. The receiver noise increases by as much as 40% in the region of overlap. We infer potential limitations for operating submillimeter-wave Nb/AlOx/Nb mixers. 相似文献