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51.
Two types of directional couplers for transverse electric (TE) modes are described: short and multihole couplers, respectively. They selectively pick one mode out of a mode mixture in an overmoded circular waveguide system. Unwanted modes are either statistically kept at low level or are suppressed by destructive interference in the coupling waveguide. Mode selectivity and directivity in multihole couplers oscillate up and down with an increasing number of holes, finally reaching a minimum of approximately 20 dB, unless there are competing modes with rational fractions of the beat wavelength. A multihole coupler for the TE02 mode (28 GHz, 63.4 mm waveguide diameter, 41 holes) and a length of 1.6 m shows a calculated directivity of 68 dB and suppresses the unwanted modes TE01 with 34 dB (24 dB), TE22 with 37 dB (45 dB), and further modes TEm (<5, m<6) with 17 dB to 34 dB in forward direction (figures in parentheses are for unwanted modes propagating in backward direction).A short directional coupler for the TE01 mode (28 GHz, 63.4 mm waveguide diameter) with 16 holes and a length of 230 mm shows a directivity of 55 to 100 dB between 27.9 and 28.1 GHz, suppressing the TE02 mode with 35 to 80 dB, the TE03 mode with 30 to 65 dB, and the TE22 mode with 30 to 70 dB. 相似文献
52.
We report the synthesis and characterisation of (S) and (R)-2′-formylcymantrenyl-17α-ethynylestradiol synthesized using the Sonogashira cross-coupling reaction between optically pure (S) and (R) 1-formyl-2-iodo cymantrenes and ethynylestradiol. (S) and (R) 1-formyl-2-iodo cymantrenes were obtained from the same precursor: (2R,4R)-4-(methoxymethyl)-2-cymantrenyl-1,3-dioxane. 相似文献
53.
M. Yamanaka Y. Takeda S. Tanigawa A. Nishizawa N. Noda J. Fujita M. Takai M. Shimobayashi Y. Hayashi T. Koizumi K. Nagasaka S. Okajima Y. Tsunawaki A. Nagashima 《International Journal of Infrared and Millimeter Waves》1980,1(1):57-76
A twin optically-pumped far-infrared CH3OH laser has been constructed for use in plasma diagnostics. The antisymmetric doublet due to the Raman-type resonant two-photon transition is reproducibly observed at 118.8 m. With the 118.8-m line, it is obtained from the frequency separation of the anti-symmetric doublet that CH3OH absorption line center is 16±1 MHz higher than the pump 9.7-m P(36) CO2 laser line center. It is shown that the Raman-type resonant two-photon transition is useful in order to get several-MHz phase modulation for the far-infrared laser interferometer. Some preliminary performances of this twin laser for the modulated interferometer are described.This work was carried out under the collaborating research program at the Institute of Plasma Physics, Nagoya University, Nagoya 464, Japan. 相似文献
54.
A rigorous side by side comparison of miniature planar potassium-selective electrodes with hydrogel and potassium hexacyanoferrate(II)/(III) doped polypyrrole (PPy/FeCN) based inner contacts is presented. The planar electrodes were manufactured by screen printing as four- and five-site arrays on ceramic substrates. These electrode arrays were incorporated into a flow-through cell, which could accommodate nine electrode sites. Two identical flow cells were connected in series and the effect of the inner contacts on the analytical performance of the respective electrodes has been critically evaluated. The time necessary to reach steady state conditions has been determined and the effect of experimental parameters (temperature, ambient light intensity, CO2, and O2 concentration of the sample) on the potential stability of the electrodes was analyzed. At controlled temperature, the drift of the planar potassium electrodes with hydrogel and PPy/FeCN solid contact were 0.11±0.02 mV h−1 and 0.03±0.007 mV h−1, respectively. The experimental data proved that there is no aqueous film formation between the PPy/FeCN film and the potassium-selective solvent polymeric membrane. 相似文献
55.
Summary The title compound was prepared from (–)(S)
p
-2,7-dibromo-1,6-methano[10]annulene by treatment withn-Bu-Li and subsequent quenching with D2O. The optical rotations at four wavelengths and the circular dichroism spectrum are reported.
Chiralität durch Deuterium-Substitution: Synthese und Circulardichroismus von (+)(R) p -2,7-Dideuterio-1,6-methano[10]annulen (Kurze Mitt.)
Zusammenfassung Die Titelverbindung wurde aus (–)(S) p -2,7-Dibrom-1,6-methano[10]annulen durch Umsetzung mitn-Bu-Li und nachfolgende Reaktion mit D2O dargestellt. Optische Rotationen bei vier Wellenlängen und das Circulardichroismus-Spektrum wurden bestimmt.相似文献
56.
This work was aimed at understanding the structure of SiO2–MO2 (M = Ti, Zr, Hf) and SiO2–HfO2–MO2 (M = Ti, Zr) materials, used as mixed oxide glass hosts for Er3+ ions in the fabrication of optical planar waveguides by sol-gel processing. This structural study was performed by Waveguide
Raman Spectroscopy (WRS), complemented with X-ray diffraction (XRD). The admixture of TiO2 to HfO2, SiO2–HfO2 and HfO2–ZrO2 compositions was found to cause precipitation of nanocrystals of tetragonal HfO2 or ZrO2, or the formation of hafnia-titania mixed crystals, depending on the HfO2/TiO2 molar ratio. 相似文献
57.
合成了含环氧基团的可交联的甲基丙烯酸甲酯和甲基丙烯酸环氧丙酯的共聚物[Poly(MMA-co-GMA)],通过FTIR,NMR,GPC,DSC和AFM等技术对其进行了表征. 结果表明,所合成的聚合物材料具有较好的成膜性; 通过热固化使引入的环氧基团开环交联,该聚合物的玻璃化转变温度(Tg)比固化前提高了24 K,同时有效地降低了聚合物的双折射率. 用Poly(MMA-co-GMA)作为包层材料,双酚A型环氧化合物作为高折射率材料, 将其引入到包层材料中形成芯层材料的折射率在波长1.55 μm处可调,其范围是1.483~1.588. 采用旋涂、 铝掩膜和氧反应离子刻蚀的方法(RIE)制得了阵列式光波导. 测试结果表明,制作的波导在1.55 μm处实现了光的单模传输,光损小于3.0 dB/cm. 相似文献
58.
Maria Crisan Mariuca Gartner Luminita Predoana Rares Scurtu Maria Zaharescu Raluca Gavrila 《Journal of Sol-Gel Science and Technology》2004,32(1-3):167-172
SiO2-ZrO2 based nanostructured multilayers films have been prepared by sol–gel processing from metallorganic precursors by low temperature inorganic polymerization reactions. Simultaneous gelation of both precursors was realized. Homogeneous and transparent films were obtained at room temperature by dip- and spin-coating on glass and silicon wafer substrates. Samples with successively deposited layers (1–3 layers) and successive thermal treatments have been also studied. Each deposited layer was thermally treated for 1 h at 300°C. The coatings were characterized by XRD, spectroellipsometry (SE), UV-VIS spectroscopy and AFM methods. The influence of substrates, number of coatings and number of thermal treatments on the optical and structural properties of the films was established. The thickness of three deposited SiO2-ZrO2 layers is about 496 nm on glass substrates and 413 nm on the silicon wafer substrate. The films deposited on glass are more porous than those deposited on silicon. The properties of optical waveguide prepared from SiO2-ZrO2 layers on silicon substrates will be discussed. 相似文献
59.
G. Carelli N. Ioli A. Moretti G. Moruzzi D. Pereira F. Strumia 《International Journal of Infrared and Millimeter Waves》1991,12(5):449-471
We have increased the frequency tunability of our CW waveguide CO2 lasers by means of an acoustooptic amplitude modulator, operating at the fixed frequency of 90 MHz. The up-shifted, or down-shifted, laser optical sideband can be generated independently by adjusting the orientation of the modulator. The efficiency is larger than 50%. The frequency tunability of the CO2 laser around each laser line is thus increased by 180 MHz. To demonstrate the possibilities of this method, a source composed of the above modulator and of a CW, 300 MHz tunable waveguide CO2 laser has been used for the search of new large offset FIR laser lines from optically pumped CH3OH and13CH3OH molecules. As a result 15 and 10 new large offset laser lines were discovered respectively. New assignments of some laser lines are also proposed. We have also measured the Stark effect, the offset, and the polarization of other already known lines. In particular a Stark effect frequency tuning of about 1 GHz is demonstrated for a laser line at 208.399 m. 相似文献
60.
A slab optical waveguide (SOWG) has been used for study of adsorption of both methylene blue (MB) and new methylene blue (NMB) in liquid–solid interface. Adsorption characteristics of MB and NMB on both bare SOWG and silanized SOWG by octadecyltrichlorosilane (ODS) were compared. Effect of pH on adsorption on MB and NMB was investigated. Binding rate constant analysis showed that both MB and NMB on bare SOWG demonstrates larger association constants than those on ODS-SOWG. Interactions of MB and NMB on bare SOWG and ODS-SOWG were analyzed by molecular mechanics calculation method. The binding energy change was in the following order: ENMB–bare > EMB–bare > ENMB–ODS > EMB–ODS. 相似文献