Millimeter and submillimeter wave measurements of complex optical and dielectric parameters of materials

These two promising millimeter wave materials were found to exhibit one order of magnitude higher absorption coefficient than the common low-loss ceramics such as alumina, fused silica and beryllia. A modular, polarizing, dispersive Fourier transform spectrometer capable of operating over the range 5 mm to 0.004 mm was used to provide a continuous spectrum of the refractive index and absorption coefficient to an accuracy of five decimal places and less than 1 percent, respectively.Partially supported by the U.S. Army Research Office under Contract Number DAAG-29-81-K-0009 and the Office of Fusion Energy, U.S. Department of Energy, under Contract W-7405-eng-26 with Union Carbide Corporation.Supported by the National Science Foundation.     

Millimeter and submillimeter wave measurements of complex optical and dielectric parameters of materials

These low loss materials were chosen for the first in this series of measurements of the complex parameters over the entire millimeter and submillimeter wavelength range of the spectrum. A modular, polarizing, dispersive Fourier transform spectrometer capable of operating over the range 5 mm to 0.004 mm was used to provide a continuous spectrum of the refractive index and absorption coefficient to an accuracy of five decimal places and less than 1 percent, respectively.Partially supported by the U.S. Army Research Office under Contract Number DAAG-29-81-K-0009 and the Office of Fusion Energy, U.S. Department of Energy, under Contract W-7405-eng-26 with Union Carbide Corporation.Supported by the National Science Foundation.     

Millimeter and submillimeter wave measurements of complex optical and dielectric parameters of materials

These coolant materials were chosen for the first in this series of measrements of the complex parameters of liquids over the entire millimeter and submillimeter wavelength range of the spectrum. The fluorocarbon coolants not reported here exhibit an order of magnitude lower loss. It is the characteristic of these liquids that the absorption coefficient increases monotonically with frequency.Partially supported by the Office of Fusion Energy, U.S. Department of Energy, under Contract W-7405-eng-26 with Union Carbide Corporation.Supported by the National Science Foundation.     

Ku波段开腔电介质高温自动测量系统

介绍了一种测量低损耗天线罩材料的开腔高温自动测量系统。该系统采用扫频方式程控标量网络分析仪对开腔进行扫频测量,得到介质加载前后腔体的谐振频率与Q值,并由此计算出被测材料的介电常数和损耗角正切;介质采用特制硅碳管加热,由温度控制器对其控制,最高温度可达1 000 ℃以上。用此系统对聚四氟乙烯和一种低损耗天线罩材料进行测量对比。结果表明,测得的聚四氟乙烯结果与文献结果相近,天线罩材料相对介电常数的实部随温度升高而增加。     

D波段双球镜准光系统测量低耗介质

采用双球镜准光腔、频谱仪和锁相返波管组建了D波段低损耗介质测试系统,该系统通过频谱仪和外置谐波混频器得到腔体谐振测试数据,并用拟合或积分方法从谐振曲线中求解出准光腔的品质因数。测得双球镜开腔的固有品质因数大于8105,使该系统在工作波段可测量损耗角正切为10-5量级的低损耗介质。用该系统测出的石英、人造金刚石和蓝宝石的介电常数和损耗,与报道的结果一致,并测得4H-SiC在132.07 GHz的介电常数实部为9.598,损耗角正切为6.110-5。     

D波段双球镜准光系统测量低耗介质

采用双球镜准光腔、频谱仪和锁相返波管组建了D波段低损耗介质测试系统,该系统通过频谱仪和外置谐波混频器得到腔体谐振测试数据,并用拟合或积分方法从谐振曲线中求解出准光腔的品质因数。测得双球镜开腔的固有品质因数大于8105,使该系统在工作波段可测量损耗角正切为10-5量级的低损耗介质。用该系统测出的石英、人造金刚石和蓝宝石的介电常数和损耗,与报道的结果一致,并测得4H-SiC在132.07 GHz的介电常数实部为9.598,损耗角正切为6.110-5。     

Index to the literature dealing with the near-millimeter wave properties of materials

An index to the literature of the near-millimeter wave (94 to 1000 GHz) properties of solid and liquid materials has been prepared which lists materials in alphabetical order, citing parameters measured, the frequency coverage, and the corresponding publication reference. An accompanying discussion deals with parameters and materials properties and present limitations in this frequency range.     

Dielectric properties of beryllia ceramics in the near-millimeter wavelength range

We report the refractive indices and absorption coefficients for four beryllia (BeO) ceramic samples. These dielectric properties have been measured over the range from 4 to 18 cm^–1 by use of a Michelson interferometer. The index n, follows the linear relationship n=0.6517 cm³/g×+0.7130 with density, , over the range 2.8<<3.0 g/cm³.     

Characterization of near-millimeter wave materials by means of non-dispersive fourier transform spectroscopy

We have used non-dispersive Fourier-transformspectroscopic techniques to measure the complex indices of refraction of materials between frequencies of 120 and 550 GHz. Results are presented for crystal quartz, crosslinked polystyrene (Rexolite 1422), glass-loaded polytetrafluoroethylene (Duroid 5880) and a nickel ferrite (Trans-Tech 2-111). These results are compared with other data on these materials in this frequency range. The accuracy of these measurements yields a considerable improvement in the near-millimeter-wave characterization of several of these materials. For materials other than crystal quartz, our results are the first measurements of their properties over the entire frequency range studied.     

Millimeter-wave absorption measurements in low-loss dielectrics using an untuned cavity resonator

Millimeter wave absorption measurements are usually complicated by scattering from the sample and by standing waves resulting from internal reflections. These problems can be largely overcome by using an untuned cavity resonator. The dielectric properties of the sample are determined from a measurement of the change in cavity Q produced by introduction of the sample into the cavity. For lamellar samples, Maxwell's equations can be used to find an explicit relationship between the change in cavity Q and the samples complex refractive index. Several measuring techniques based on the use of lamellar samples are presented, and their characteristics are illustrated both analytically and by laboratory measurements at 70 GHz on PTFE, polyethylene and plexiglas.On leave from Département de Physique et Laboratoire de recherche en optique et laser, Université Laval, Québec, Qué., Canada, G1K 7P4     

热波法测良导体热导率实验中高频热波影响的分析与消除

在热波法测良导体热导率的实验中,由于高频热波的影响,使实验结果产生很大的误差.现提出一种可有效解决高频热波造成误差的方法,即利用计算机数字滤波滤去高频波,提取基波,从而提高了实验精度.     

Resonant coupling in the van der Waals interaction between an excited alkali atom and a dielectric surface: an experimental study via stepwise selective reflection spectroscopy

We present a detailed experimental study of the evaluation of the van der Waals (vW) atom-surface interaction for high-lying excited states of alkali-metal atoms (Cs and Rb), notably when they couple resonantly with a surface-polariton mode of the neighbouring dielectric surface. This report extends our initial observation [Phys. Rev. Lett. 83, 5467 (1999)] of a vW repulsion between Cs(6D_3/2) and a sapphire surface. The experiment is based upon FM selective reflection spectroscopy, on a transition reaching a high-lying state from a resonance level, that has been thermally pumped by an initial one-photon step. Along with a strong vW repulsion fitted with a blue lineshift, -160±25 kHz μm³ for Cs(6D_3/2) in front of a sapphire surface (with a perpendicular c-axis), we demonstrate a weaker vW repulsion (-32±5 kHz μm³) for Cs(6D_3/2) in front of a YAG surface, as due to a similar resonant coupling at 12 μm between a virtual atomic emission (6D_3/2-7P_1/2) and the surface polariton modes. A resonant behaviour of Rb(6D_5/2) in front of a sapphire surface exists also because of analogous decay channels in the 12 μm range. Finally, one demonstrates that fused silica, nonresonant for a virtual transition in the 12 μm range and hence weakly attracting for Cs(6D_3/2), exhibits a resonant behaviour for Cs(9S_1/2) as due to its surface polariton resonance in the 8-9 μm range. The limiting factors that affect both the accuracy of the theoretical prediction, and that of the fitting method applied to the experimental data, are discussed in the conclusion. Received 16 January 2003 / Received in final form 25 March 2003 Published online 5 May 2003     

Optical properties of polymer poly(phthalazinone ether sulfone ketone) film waveguide

The optical properties of novel polymer poly(phthalazinone ether sulfone ketone, PPESK) film waveguide are studied by prism coupler. The optical properties of PPESK-8020, including refractive index, birefringence, thermo-optical coefficient and optical loss, are demonstrated. This kind of material has the advantages of low optical loss (less than 0.24 dB/cm at 1310 nm and 0.52 dB/cm at 1550 nm) and high thermal stability (1% weight loss temperature: 488 ℃). Due to these excellent properties, it may have great potential in optical waveguide applications.