聚合物电光调制器行波电极系统

设计了20 GHz聚合物光波导电光调制器CPW电极系统。制作和测试了分别用 Si、石英、玻璃做衬底的CPW电极系统。结果表明,石英衬底CPW电极质量最好,在中心电极宽度 W=20μm、电极间距G=50μm和电极厚3μm条件下,其实测损耗系数α0=0.32 dB·cm-1·GHz-0.5,实测微波等效折射率Nm=1.689,与理论值符合。在偏离此α0 和 Nm±10%的情况下,对于互作用区电极长度为 L=23.7 mm的调制器,估算带宽仍大于37 GHz。讨论了Si衬底CPW电极传输损耗很大的原因。     

传输线电极型硅基电光调制器研究进展

首先对不同类型光调制器性能做了简单比较,并结合近几年的研究进展情况,对各种电光调制器优缺点进行介绍,尤其对其中具有广泛应用前景的硅基电光调制器作了详尽的介绍,最后讨论了传输线电极设计对各类电光调制器性能的影响,并介绍了近几年在改善电光调制器的调制带宽方面的研究进展。     

新型行波电极超宽带LiNbO_3电光调制器的优化设计

采用有限元法和增量电感公式对一种新型电极结构的电光调制器进行了理论分析和设计.计算中对损耗系数进行了修正.计算结果表明这种结构可以灵活地实现相速匹配和有效降低电极损耗.是一种具有超宽带潜力的调制器.用带宽和驱动功率的比值作为衡量调制器特性优劣的标准.得到了这种电极结构的一些优化尺寸.并从中发现适当增大电极间隙有利于提高器件性能.利用优化结果.给出了一带宽为100GHz.半波电压为6V的调制器设计例子.     

高速InP基半导体电光调制器行波电极结构研究

对PIN型和NIN型两种InP基Mach-Zehnder电光调制器的电极结构进行了数值仿真研究,从而确定出适于这两种电光调制器的行波电极结构。仿真结果表明,NIN型电光调制器可采用简单的单臂类微带电极,而PIN型电光调制器需采用周期容性负载电极,以达到良好的阻抗匹配特性和传输特性。进一步地,提出了将串联推挽式行波电极结构应用于PIN型电光调制器,可以简化制作工艺并获得良好的微波特性。     

聚合物共面波导行波电极电光调制器

用聚合物材料BPAN-NT设计并初步成功制作了共面波导(CPW)行波电极电光调制器。用反应离子刻蚀(RIE)的方法制作脊波导,通过电晕极化使芯层有电光效应,利用电镀方法制作厚行波电极。对调制器的各项特性参数进行了测试,测得调制器的微波损耗系数0α=0.9 dB/cm.(GHz)1/2、在1.317μm波长上Vπ=250 V,由此算得芯层材料的电光系数3γ3=3.7 pm/V,同时测得消光比为13.49dB、插入损耗为18.6 dB,在8 GHz的微波频率上观察到了调制光信号,理论计算3 dB光调制带宽为43.77 GHz。     

LiNbO3电光调制器行波电极微波等效折射率的测量

LiNbO3电光调制器的设计中,行波电极的微波等效折射率是一个重要的参数。该文通过自行设计的微波探针架及探针,采用差值的方法,在微波网络分析仪上对样品CPW电极的微波等效折射率进行了测量,分析了实测值与理论计算值的偏差,给出了修正因子,研究了微波等效折射率随频率变化的色散现象,并对这种测量方法进行了误差分析,提出了减小误差的方法。     

一种低损耗硅基MZ电光调制器的驱动电极设计

为了满足高数据带宽的硅光互联应用要求,高速硅光调制器的设计至关重要.本文基于IMEC的硅光子SOI工艺,提出了一种低损耗高带宽的行波MZ调制器的驱动电极.在详细分析了趋肤效应、行波损耗、邻近效应等物理效应对行波电极信号完整性的影响的基础上,通过在行波电极上增加一定宽度的顶层金属的方法,使MZ调制器的低频损耗降低了13%,高频损耗降低了5%,并使电光调制3 dB带宽提高至28 GHz.     

集成光学M—Z调制器的行波电极电场的有限元分析

报道了一种运用MATLAB语言对集成光学M－Z调制器行波电极的电场进行有限元分析的方法,得到了令人满意的计算结果,程序的运算时间缩短到原来的1／12。     

LiNbO3电光调制器行波电极微波等效折射率的测量

LiNbO3电光调制器的设计中，行波电极的微波等效折射率是一个重要的参数。该文通过自行设计的微波探针架及探针，采用差值的方法，在微波网络分析仪上对样品CPW电极的微波等效折射率进行了测量，分析了实测值与理论计算值的偏差，给出了修正因子，研究了微波等效折射率随频率变化的色散现象，并对这种测量方法进行了误差分析，提出了减小误差的方法。     

电光行波调制器电极特性参量的计算

本文采用简洁的静态求解的方法,考虑了电极厚度和缓冲层对电极特性参量的影响,对四种常用的LiNbO_3光波导行波调制器电极的特性参量进行了分析计算,并得出了一些对设计和优化较有意义的结论。     

40 Gb/s differential traveling wave modulator driver

In this letter a MMIC differential traveling wave driver for 40 Gb/s electro-absorption modulation driver is presented. The driver delivers 2.7 Vp-p or 2.4 V eye amplitude at each output into 50 /spl Omega/ load. The driver has high gain (>20 dB), a 3 dB bandwidth of 45 GHz, and rise/fall times of only 10/9 ps, respectively. The circuit uses a single -5.0 V power supply and consumes 1.8 W of dc power. The driver also features cross-point control and output amplitude control functions.     

Diamond-studded helical traveling wave tube

A novel method of millimeter-wave traveling wave tube (TWT) slow-wave circuit fabrication, employing laser micromachining and the in situ growth of diamond studs as an insulating dielectric, has been developed, which would enable a new class of very wideband, low distortion, high-efficiency amplifiers. Because the slow-wave circuit is supported by an array of diamond studs, rather than the conventional dielectric rods, we have named this novel device the diamond-studded TWT. Diamond strips have been successfully grown on a molybdenum tube and a diamond-studded helix has been produced using laser micromachining. Computer analysis of the slow-wave structure indicate that this fabrication technique leads naturally to a circuit with nearly flat dispersion over a frequency range, in some configurations, of more than four octaves. Typically, wide bandwidth can only be achieved by reducing efficiency; however, this fabrication technique increases the interaction impedance of the circuit, enabling high efficiency operation without sacrificing bandwidth. The very low dispersion also results in a coupling impedance that is relatively insensitive to frequency that may enable low reflection coupling over a wide frequency band. The resulting slow-wave circuit is essentially a brazed structure and, therefore, inherently robust thermally and mechanically. The manufacturing technology being pursued is applicable to any millimeter-wave helical or helix-derived TWT.     

Development of linear traveling wave tubes for telecommunicationsapplications

Traveling wave tubes (TWTs) designed for telecommunications applications in multichannel power amplifiers (MCPAs) are required to have high linearity, low intermodulation distortion, high efficiency and high power outputs. The linearity of the TWT can be greatly improved by operation of the tube significantly backed off from saturation and by optimization of the design of the helix circuit. This results in two tone intermodulation products that are 25 to 40 dB below the carrier level, depending on the amount of back-off selected. However, operation backed off from saturation results in a greatly reduced efficiency of the TWT, which must be compensated for by optimal circuit and collector design. Several L-band and S-band Hughes TWTs have been developed for telecommunications applications and feature saturated power levels of up to 2 kW and average power of over 600 W with overall efficiencies of over 20% at 10 dB back-off and 40% at 6 dB back-off. These tubes provide high average power, high efficiency amplification with modest size and reduced cooling requirements compared to solid state amplifiers     

Analytical timing model for inductance-dominant interconnect based on traveling wave propagation

As accurate and efficient timing prediction is very important for integrated circuit design, an analytical timing model for inductive-effect dominated resistance-inductance-capacitance (RLC) transmission line with resistive driver and capacitive load is proposed by virtue of traveling wave propagation and perturbation technique. This model is theoretically stable and computationally efficient. Comparison with other analytical and SPICE models illustrates that this timing model can achieve excellent accuracy for inductance-dominant interconnect. Incorporating with decoupling technique, this model could be readily extended to coupled interconnects.     

Integrated optic electrooptic modulator electrode analysis

Integrated optical (IO) switches and modulators are based on the electrooptic effect obtained by applying a voltage between electrodes fabricated on the surface of a crystal (for example, LiNbO3). In this paper, we calculate the change in the optical propagation constant in single modeZ-cut LiNbO3:Ti-diffused waveguides for a variety of electrode configurations. These calculations are compared to experimental data from IO devices. The calculations predict the observed variations in switching voltage with wavelength and electrode separation.     

Multigigahertz guided wave magnetooptic modulator

We propose a magnetooptic modulator based on a thin-film iron garnet material. The Landau-Lifshitz equation, which governs magnetization dynamics, is combined with a beam propagation method to evaluate the performance of the device in the multigigahertz range. Bandwidth considerations and temporal response are discussed     

Rational function based predistorter for traveling wave tube amplifiers

A new scheme for the compensation of traveling wave tube amplifier nonlinearities is proposed and analyzed in this paper. The approach is based on rational function models of the amplifier AM-AM and AM-PM conversions. Amplitude and phase predistortion are performed separately. The phase predistortion is a function of the output of the amplitude predistortion part of the predistorter, instead of the input signal amplitude of the predistorter. Computer simulations reveal an improved performance compared to published techniques and suggest that with the proposed technique the transmit power amplifier can operate far into its nonlinear region. The transfer characteristics of the cascade of the amplifier and the proposed predistorter match the optimum transfer characteristics of a saturating device.