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排序方式: 共有271条查询结果,搜索用时 9 毫秒
71.
Properties of index-guided PCF with air-core 总被引:5,自引:0,他引:5
In the paper, index-guided triangular PCF with air-core is introduced which guides light by total internal reflection (TIR) when the air-core is smaller than the air holes in cladding. Properties of dispersion and leakage loss are investigated using finite-element method. The total dispersion curve gets more flattened and leakage loss increases significantly as the air-core diameter increases. High birefringence PCF with elliptical air-core is put forward and the birefringence increases with the ellipticity of the air-core. 相似文献
72.
光子晶体光纤(PCF)与普通单模光纤(SMF)的低损耗熔接技术是光子晶体光纤走向实用化必须解决的关键技术问题。提出一种基于光纤拉锥模场匹配技术的光子晶体光纤低损耗熔接的新方法,利用熔融拉锥机对模场不匹配的两类PCF进行预处理,结合常规电弧放电熔接技术对三种不同类型的PCF与SMF的熔接损耗进行实验研究。在实验中通过精确控制熔融拉锥机各种参数,实现了不同模场直径PCF和SMF的模场匹配,该方案同时通过优化各种电弧放电参数,使熔接后的损耗降到了0.3dB以下,实现了PCF-SMF之间低损耗、高强度的熔接,满足了不同模场PCF实际应用的要求,具有很好的潜在应用价值。 相似文献
73.
We demonstrate a 7-bit photonic true-time-delay (TTD) system which uses an 8 × 8 micro-optical-electro- mechanical system (MOEMS) optical switch for phased array antennas (PAAs) beamforming applications. The switch controls the optical signal to pass by the fiber delay lines (FDLs) of different lengths. Different time delays between adjacent channels are obtained due to the chromatic dispersion of FDLs. Therefore, the system cannot be disturbed by the environment. The measured time delay responses are nearly linear with the wavelength spacing between optical carriers as well as the lengths of FDLs, which agrees well with the theoretical analysis. 相似文献
74.
用于投影机的发光二极管照明单元 总被引:2,自引:1,他引:2
目前的投影机光源——高压汞灯存在寿命短、色温高、存在有害光线、发热集中等缺点,严重制约了投影机进入家庭应用领域。发光二极管的最近发展为其作为高压汞灯的替代光源提供了可能性。提出了一种由一个发光二极管、一个准直镜、一个前蝇眼透镜和一个后蝇眼透镜组成的用于投影机的发光二极管照明单元,由数个照明单元加上会聚透镜则构成一个基本的照明系统。发光二极管的发光经准直镜压缩光束发散角后被前蝇眼透镜分割为多个细光束,会聚透镜将每个细光束都叠加会聚到显示芯片上,实现光能量的会聚和光场再分布.以满足投影机对光通量和光场均匀性等方面的要求,后蝇眼透镜用于与后续光路的匹配。作为照明单元的一个应用实例,文中分析了一种单片式硅上液晶投影机。 相似文献
75.
A novel non-feedback precoder circuit for high-speed parallel optical differential quadrature phase shift keying (DQPSK) modulation is proposed. The alternative control signal is introduced in replacement of the conventional feedback one, which eliminates the speed limitation due to the electronic propagation delay. The proposed precoder consists of four differential encoders, an exclusive OR gate, a cross switch, and delay lines. It is demonstrated by a true pseudo random bit sequence (PRBS) transmission at 20 Gb/s. 相似文献
76.
Qiu Weisheng 《组合设计杂志》1995,3(6):393-397
In this article we prove that in the case n = 4n1 if (v,2 · 7 · 31) = 1 and v is not divisible by 15, then the Second Multiplier Theorem holds without the assumption n1 > λ. This improves a result due to McFarland. © 1995 John Wiley & Sons, Inc. 相似文献
77.
The use of 5H-3-oxa-octafluoropentanesulfonyl fluoride (HCF2CF2OCF2CF2SO2F) as a novel and efficient condensing reagent for esterification of carboxylic acids with alcohols and amidation of carboxylic acids with amines in the presence of 1,3-diazabicyclo[5.4.0]-undec-7-ene (DBU) is reported. HCF2CF2OCF2CF2SO2F cannot serve as a condensing agent for anhydridization of carboxylic acids, however, HCF2CF2OCF2CF2SO2F/(CH3)3SiCN system can mediate anhydridization of some aromatic carboxylic acids. 相似文献
78.
Phase drift cancellation of remote radio frequency transfer using an optoelectronic delay-locked loop 总被引:1,自引:0,他引:1
In this Letter, we propose a phase drift cancellation method for remote radio frequency transfer. Phase fluctuation along the transmission fiber, which is induced by temperature and pressure changes, is measured and compensated by a heterodyne optoelectronic delay-locked loop. The control loop consists of a heterodyne optoelectronic phase detector, a microwave delay module, and the loop filter. We demonstrate the concept by transmitting a 10?GHz microwave frequency over 50?km single-mode fiber, with subpicosecond jitters measured at the remote end. 相似文献
79.
80.
Wai CM Liao YJ Liao W Tian G Addleman RS Quach D Pasilis SP 《Dalton transactions (Cambridge, England : 2003)》2011,40(18):5039-5045
Uranium dioxide can be dissolved directly in an imidazolium-based ionic liquid (IL) at room temperature with a tri-n-butylphosphate(TBP)-HNO(3) complex. The dissolution process follows pseudo first-order kinetics initially. Raman spectroscopic studies show the dissolved uranyl ions are coordinated with TBP in the IL phase with a molar ratio of (UO(2))(2+) : TBP = 1 : 2. The dissolved uranyl species can be effectively transferred to a supercritical fluid carbon dioxide (sc-CO(2)) phase. No aqueous phase is formed in either the IL dissolution or the supercritical fluid extraction process. Absorption spectra of the extracted uranyl species in the sc-CO(2) phase suggests the presence of a UO(2)(TBP)(2)(NO(3))(2) and HNO(3) adduct probably of the form UO(2)(TBP)(2)(NO(3))(2)·HNO(3). The adduct dissociates in a water-dodecane trap solution during pressure reduction resulting in UO(2)(TBP)(2)(NO(3))(2) collected in the dodecane phase. 相似文献