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1.
低阻硅基厚膜聚酰亚胺上共面波导的损耗特性 总被引:3,自引:1,他引:2
制备了一种低阻硅基厚膜聚酰亚胺上的高性能共面波导传输线 ,并从理论上分析了传输线损耗的成因及其计算方法。聚酰亚胺膜厚 1 1 .5 μm的低阻硅 (0 .5 Ω·cm)上的共面波导传输线在 1 0 GHz下插入损耗为3 .5 d B/cm。然而 ,相同衬底上 ,无聚酰亚胺膜的共面波导传输线在 1 0 GHz下插入损耗为 5 0 d B/cm,损耗特性明显比前者差。测试结果表明聚酰亚胺层的介入能有效地改善传输线的损耗特性 ,且损耗随着聚酰亚胺膜厚的增加而降低。 相似文献
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根据最佳端焦耦合原理,建立了1.3μm波段光波导损耗测量系统,在测得系统附加透射损耗和G—PD响应特性曲线的基础上,对宽6μm的T_i扩散L_iNbO_3单模波导的传输损耗进行了测量评价,测量误差<±0.07dB/cm。 相似文献
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建立了弯曲光纤的二维轴对称有限元分析模型,对初始光纤弯曲性能进行了有限元分析,分别计算其弯曲损耗,有效模场面积和连接损耗;选取芯层到下陷层距离b,下陷层宽度c,下陷层深度t,空气孔孔径r为设计变量,以弯曲损耗和连接损耗最小为目标,利用正交试验和灰度关联分析相结合的方法对光纤弯曲性能进行了多因素多目标优化设计。研究结果表明:优化后光纤弯曲损耗从0.127 8 dB/m减小到1.749 810-4 dB/m;有效模场面积从94.741 m2减小到82.37 m2;连接损耗由0.174 3 dB减小到5.80510-4 dB。与标准单模光纤对比发现,新型光纤在弯曲半径为3 mm的情况下,有效模场面积从209.21 m2减小到82.3 m2,连接损耗从7.535 8 dB减小到5.80510-4 dB,大大地降低了光纤的连接损耗。新型光纤在小半径弯曲情况下,也能保证系统的传输质量。 相似文献
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研究了金属-介质-金属(MDM)型表面等离子体激元(SPP)光波导的电磁特性。理论计算结果表明,对于633nm的TM偏振入射光,当介质膜层厚度小于85nm时,波导中只能激发产生一阶SPP模(基模),其余高阶模全部截止。随着介质膜厚度增加,高阶SPP模逐渐被激发产生。当介质膜层厚度较小时,SPP模的有效折射率的实部随阶数的增加而减小,而虚部则随阶数的增加而增加,SPP基模具有最大传输距离。然而,当MDM波导中的介质层厚度超过0.555μm时,由于三阶SPP模的电磁场主要集中在离金属层相对较远的介质层中,其有效折射率的虚部具有最小值,具有最大的传输距离,而非基模。当入射光波长为633nm介质层厚度为0.9μm时,Ag/SiO2/Ag光波导中三阶SPP模的传输距离达到约150μm。 相似文献
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Emilio Alessandro Nanni Sudheer Kumar Jawla Michael A. Shapiro Paul P. Woskov Richard J. Temkin 《Journal of Infrared, Millimeter and Terahertz Waves》2012,33(7):695-714
Applications of high-power Terahertz (THz) sources require low-loss transmission lines to minimize loss, prevent overheating
and preserve the purity of the transmission mode. Concepts for THz transmission lines are reviewed with special emphasis on
overmoded, metallic, corrugated transmission lines. Using the fundamental HE11 mode, these transmission lines have been successfully implemented with very low-loss at high average power levels on plasma
heating experiments and THz dynamic nuclear polarization (DNP) nuclear magnetic resonance (NMR) experiments. Loss in these
lines occurs directly, due to ohmic loss in the fundamental mode, and indirectly, due to mode conversion into high order modes
whose ohmic loss increases as the square of the mode index. An analytic expression is derived for ohmic loss in the modes
of a corrugated, metallic waveguide, including loss on both the waveguide inner surfaces and grooves. Simulations of loss
with the numerical code HFSS are in good agreement with the analytic expression. Experimental tests were conducted to determine
the loss of the HE11 mode in a 19 mm diameter, helically-tapped, three meter long brass waveguide with a design frequency of 330 GHz. The measured
loss at 250 GHz was 0.029 ± 0.009 dB/m using a vector network analyzer approach and 0.047 ± 0.01 dB/m using a radiometer.
The experimental results are in reasonable agreement with theory. These values of loss, amounting to about 1% or less per
meter, are acceptable for the DNP NMR application. Loss in a practical transmission line may be much higher than the loss
calculated for the HE11 mode due to mode conversion to higher order modes caused by waveguide imperfections or miter bends. 相似文献
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《Microwave and Wireless Components Letters, IEEE》2008,18(2):79-81
Conventional rectangular metallic waveguides are seldom used at frequencies higher than twice the cutoff frequency because of higher mode propagation. Single-mode propagation is available for a metallic waveguide with arrayed dielectric rods at the center of the waveguide in the frequency under twice the cutoff frequency region using the TE20 mode, and in the frequency over twice the cutoff frequency region using the TE2o mode. If the metallic waveguide and dielectric loss tangent are assumed to be WR-90 (fc ap6.55 GHz) and 3times10-4, respectively, then the attenuation constants are smaller than 0.25 dB/m in the frequency range from 7 to 10 GHz, 15 to 16.5 GHz, and from 17.2 to 21 GHz. 相似文献
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The propagation properties of terahertz (THz) waveguide plastic hollow fiber have been investigated in this paper. The effects of radiation frequency, bore diameters and dielectric coating layers on the waveguide property have been shown and discussed. The results show that the attenuation loss of TM mode increases and that of TE mode decreases as radiation frequency increases. The attenuation loss decreases with the increasing of fiber bore diameter. The attenuation loss decreases as the refractive index of dielectric coating layer and the ratio of the refractive index of outer dielectric layer to that of inner dielectric layer increase. 相似文献
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Ugo Siciliani de Cumis Ji-Hua Xu Carlos M. Bledt James A. Harrington Alessandro Tredicucci Miriam S. Vitiello 《Journal of Infrared, Millimeter and Terahertz Waves》2012,33(3):319-326
We coupled linearly polarized and azimuthally polarized Terahertz quantum cascade lasers (QCLs) to the low-loss optical modes
of hollow core waveguides having a sequence of different metallic or dielectric inner coatings. The latter waveguides have
been specifically designed to force the propagation of a dominant optical mode once the thickness (d) of the inner dielectric
coating is properly chosen. Our results demonstrate that both the TE01 and the TE11 modes can be easily converted to a hybrid
one when d > 6 μm allowing the propagation of THz QCL beams with transmission losses as low as 1.5 dB/m, bending losses < 1.1 dB
and reasonably high coupling efficiencies (87%). 相似文献
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Chao-Yi Tai Sheng Hsiung Chang TsenChieh Chiu 《Photonics Technology Letters, IEEE》2007,19(19):1448-1450
We present the design of an ultra-compact polarization beam splitter where three symmetrical dielectric channel waveguides are hybrid integrated with Au plasmonic waveguide arrays. Ultra-wideband operation over 50 THz with the insertion loss less than 2 dB for both transverse electric and transverse magnetic mode are predicted. The extinction ratio is better than 15 dB for both polarizations and it is realizable on a chip size as small as 0.93times4.2 mum2. 相似文献
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太赫兹(THz)波位于微波与红外光波之间,现有微波和光波段波导技术应用正在向THz波段拓展。但是,由于水汽对THz波的强吸收及制造工艺等原因,THz器件主要是平面结构,而THz源及其传输需要用矩形波导。因此,矩形波导与共面波导之间的转换结构成为决定元件和系统性能的关键部分。该设计利用脊波导进行阻抗匹配及电磁场模式转换,实现THz波矩形波导到共面波导的高效率耦合。结果表明,在0.2~0.4 THz频段内,该转换结构的传输系数(S21)高于?3 dB,可以对THz电磁场进行高效率转换。该结果可用于太赫兹分子探测、太赫兹通信等领域,为0.2 THz以上太赫兹的模式转换提供了一种可行方案。 相似文献
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以聚甲基丙烯酸甲酯(PMMA)材料为基质,设计了一种空芯多孔包层结构的太赫兹光纤,中心的大孔缺陷用于传输太赫兹波,周围四层小孔可以将太赫兹波的传播限制在缺陷内部。利用COMSOL软件对光纤的损耗特性进行仿真分析发现,光纤在0.6 THz的泄露损耗低于0.1 dB/m,具有良好的传输特性。和金属波导口可以当作天线辐射电磁波的原理相似,光纤的端面也可以作为天线将内部传输的太赫兹波向外辐射,通过仿真分析,天线在0.59~0.61 THz的回波损耗低于-25 dB,方向性系数大于20 dB,半功率波束宽度约为13。 相似文献
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Ling Liao Desmond R. Lim Anuradha M. Agarwal Xiaoman Duan Kevin K. Lee Lionel C. Kimerling 《Journal of Electronic Materials》2000,29(12):1380-1386
Signal propagation delays dominate over gate delays in the ever-shrinking ultra large scale integrated (ULSI) circuits. Consequently,
silicon-based monolithic optoelectronic circuits (SMOE) with their light speed signal propagation can provide unique advantages
for future generations of microprocessors. For such SMOE circuits, we need optical interconnects compatible with silicon technology.
Strip waveguides consisting of polycrystalline silicon (polySi) clad with SiO2 offer excellent optical confinement and ease of fabrication that are ideal for such interconnect applications. One major
challenge with using this material system, however, is its insertion loss. In this paper we provide techniques for minimizing
optical transmission losses in polySi strip waveguides. Our previous work using polySi strip waveguides, showed an optical
transmission loss of 15 dB/cm at λ=1.55 μm, which is a communication wavelength of choice in optical fibers because it represents an absorption minimum. Similar
measurements in crystalline silicon strip waveguides1 yielded transmission losses of less than 1 dB/cm. Hitherto, in decreasing loss from 77 dB/cm to 15 dB/cm, we had minimized
loss from surface scattering by improving the film surface morphology, and decreased bulk absorption with hydrogen passivation.
In this paper we report a further reduction in the residual bulk loss from 15 dB/cm to 9 dB/cm. By experimenting with different
waveguide core dimensions, we find that the contribution of bulk loss towards net transmission loss decreases with waveguide
core thickness. Additionally, high temperature treatment provides strain relief in the polySi, decreasing transmission loss.
Annealing in an oxygen ambient is not recommended because it always increases transmission loss. Hydrogen passivation improves
transmission, attributable to passivation of light-absorbing dangling bond defect sites present at polySi grain boundaries.
Together, these methods have resulted in the lowest measured loss value of 9 dB/cm at λ=1.55 μm. Since integrated SiGe and Ge photodetectors are more efficient at shorter wavelengths like λ=1.32 μm, transmission loss is also measured at λ=1.32 μm. Losses at the two wavelengths (1.32 μm and 1.55 μm) are similar when defects and stress in the waveguides are minimized. 相似文献
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A terahertz (THz) waveguide band-pass filter using an iris inductive window coupled structure was designed and fabricated. The filter was designed at 0.22 THz with a pass band of 20 GHz. The measured results show that the center frequency is 0.218 THz with a pass band of 0.205 THz to 0.231 THz, the minimum insertion loss is 1.26 dB at 0.224 THz, and the return loss is less than 13.1 dB. The stop-band suppression is 65.6 dB at 0.193 THz and 51.8 dB at 0.243 THz, respectively, which means a good performance of high stop-band suppression. A good agreement exists between the measured S-parameters and the simulated ones, especially in the upper band. The proposed THz waveguide filter has potential applications in THz communications. 相似文献