WDM-POLSK Transmission Systems by Using Semiconductor Optical Amplifiers

The authors demonstrate the potential of using POLarization Shift Keying (POLSK) modulation format combined with semiconductor optical amplifiers (SOAs) in wavelength division multiplexing (WDM) transmission systems. The constant intensity of the POLSK modulation format allows for substantial removal of cross-gain-modulation impairments in SOAs so that practical amplifier spacing values (more than 100 km) are demonstrated in various different experimental configurations. Record WDM transmission experiments at 10 Gb/s by using SOA-based amplification are presented in short and medium reach system architectures using either single mode fiber or nonzero dispersion shifted fiber     

大功率半导体光放大器的耦合工艺研究

针对高速大功率半导体激光器,设计了主振激光器与半导体光放大器分立集成的高速大功率半导体激光器组件,并对其中半导体光放大器(SOA)的光纤耦合技术进行了研究,采用单模光纤耦合技术以及光路可逆原理设计了SOA的注入端耦合光路,实现了主振激光器到SOA的高效注入,耦合效率大于50%,采用微透镜组技术设计了SOA输出端的耦合光路,实现了Φ62.5μm的光纤耦合输出238mW。同时针对光纤耦合工艺,利用Ansys软件对耦合结构进行了激光焊接耦合工艺的热应力分析,得到了优化的焊接工艺条件,并对耦合中存在的应力进行了释放处理,有效提高了输出功率的稳定性。     

超大容量光传输系统

结合大量的实际测试结果,分析了目前最新的32/40×10Gbit/s波分复用(WDM)系统的性能及技术特点,并简要介绍了光通信领域的几项新技术及其发展趋势。     

Using High Frequency Operational Amplifiers for Low Noise Design

In this paper we present a comprehensive noise and stability analysis of both the current feedback and the voltage feedback op-amp when connected as transimpedance amplifiers with capacitive current sources. It is generally assumed that the current feedback op-amp is noisier than the voltage feedback op-amp; we show how external component values play an important role in determining the total equivalent input noise current spectral density and show that the voltage feedback op-amp may, in certain cases, be noisier than the current feedback op-amp. Both amplifier types are compared in terms of stability, noise and bandwidth; we find that the current feedback op-amp is particularly suited for operation as a transimpedance amplifier. Theoretical analysis is confirmed by simulations of equivalent circuits of the current feedback op-amp and the voltage feedback op-amp, and simulations of the macro models of two high performance commercially available op-amps, namely the Elantec EL2260 current feedback op-amp and the Elantec EL2244 voltage feedback op-amp.     

大容量副载波复用光纤传输技术

本文分析、讨论了光纤副载波多路复用(SCM)传输系统中副载波频率配置的原理。根据传输容量的大小和光器件技术参数,以产生二阶互调干扰最小为准,提出了几种副载频率配置的方法,它适用超宽频带中SCM系统的设计,并能用来估算在光器件调制频宽内SCM系统应用的潜力。     

Generalized Solutions for Optical Maser Amplifiers

The optical maser amplifier is treated from the transient analysis point of view using the Laplace transform method as opposed to the conventional sinusoidal steady-state analysis that sometimes leads to inconsistent results especially for the region beyond threshold. Firstly, the wave equations are expressed in terms of laplace transforms, and then the generalized solutions for both the transmission and the reflection mode of operation are derived taking the transient terms into account. Finallly, the inverse laplace transforms are obtained yielding the generalized solutions in terms of real-time functions. In order to emphasize the point of the argument and also to compare the results of the usual sinusoidal steady-state analysis, use is made of the simplest possible model of a one-dimensional system consisting of three media, air, active medium, and air. An incident coherent transverse electromagnetic wave, which falls normally on the surface of the system, is assumed. The generalized solutions derived agree,in the region below threshold, exactly with that of the sinusoidal steady-state analysis obtained previously by other investigators. However, for the region beyond critical threshold, the generalized solutions indicate that the device goes into a state of self-oscillation with oscillation frequencies that strictly coincide with those of the Fabry-Perot type resonator. Thus, the limitation of applicability of the conventional sinusoidal steady-state analysis is clarified. Some remarks are also given on the design problem of optical maser amplifiers in connection with the transient terms involved.     

光端机用厚膜集成电路的研制

采用厚膜集成技术研制、开发了用于光纤通信传输端机用的光源驱动器和视频分配器厚膜电路，该电路在０～３０ＭＨｚ频率范围工作，完全符合技术指标要求     

分布光纤拉曼放大器对光通信系统传输性能的改善

考察了后向抽运分布光纤拉曼放大器 (B DFRA)对光通信系统传输性能的改善。分别讨论了B DFRA的两种可能用途 :1)作为第一级预放器与掺铒光纤放大器 (EDFA)及光接收机一同构成接收终端。 2 )在一个有中继的长距离光通信系统中作为各级EDFA的预放器。针对这两种用途分别计算出B DFRA对系统性能的影响 ,并给出选择抽运功率的原则     

FTTH光接收机前置放大器的设计与改进

本文通过分析国内外FTTH光接收机应用前景和普通光接收机的前置放大器基础上，用MOS管替代通用放大模块。设计并经过优化改进找到了一款适合FTTH的CATV光接收机前置放大器。通过测试，性能指标完全符合要求．具有很好的实用价值。     

多路高速光纤图像传输系统设计及实现

设计了基于内嵌高速收发器RocketIO的现场可编程门阵列(FPGA)的多路光纤图像传输系统,能够对Camera Link接口模式的高速大容量图像数据进行实时传输。详细给出了系统总体结构设计、硬件实现中需要注意的问题和若干关键的软件功能模块,包括并口转换模块、图像传输控制逻辑和RocketIO的设计和配置。实验显示传输系统的三通道有效数据传输速率达7.2Gb/s,传输线路稳定可靠,满足光电探测设备对传输带宽的需求。     

FTTH光接收机功率放大器的设计与改进

在分析国内外FTTH光接收机应用前景和普通光接收机的功率放大器基础上,用MMIC替代通用放大模块,设计并经过优化改进找到了一款适合FTTH的CATV光接收机功率放大器.通过测试,性能指标完全符合要求,具有很好的实用价值.     

Quantum-Dot Semiconductor Optical Amplifiers

This paper reviews the recent progress of quantum-dot semiconductor optical amplifiers developed as ultrawideband polarization-insensitive high-power amplifiers, high-speed signal regenerators, and wideband wavelength converters. A semiconductor optical amplifier having a gain of > 25 dB, noise figure of < 5 dB, and 3-dB saturation output power of > 20 dBm, over the record widest bandwidth of 90 nm among all kinds of optical amplifiers, and also having a penalty-free output power of 23 dBm, the record highest among all the semiconductor optical amplifiers, was realized by using quantum dots. By utilizing isotropically shaped quantum dots, the TM gain, which is absent in the standard Stranski-Krastanow QDs, has been drastically enhanced, and nearly polarization-insensitive SOAs have been realized for the first time. With an ultrafast gain response unique to quantum dots, an optical regenerator having receiver-sensitivity improving capability of 4 dB at a BER of 10^-9 and operating speed of > 40 Gb/s has been successfully realized with an SOA chip. This performance achieved together with simplicity of structure suggests a potential for low-cost realization of regenerative transmission systems.     

Organic Semiconductor Optical Amplifiers

Organic semiconducting materials have been researched for novel optoelectronic devices due to their efficient light emission and high gain properties. Such devices range from organic light-emitting diodes and solar cells to lasers and amplifiers. This paper explores the research carried out on one of these devices: organic semiconductor amplifiers that have shown to give high gains of 20–40 dB in solution and solid state.      

Systematic Approach for Design of Broadband,High Efficiency,High Power RF Amplifiers

This paper demonstrates a systematic approach for the design of broadband, high efficiency, high power, Class‐AB RF amplifiers with high gain flatness. It is usually difficult to simultaneously achieve a high gain flatness and high efficiency in a broadband RF power amplifier, especially in a high power design. As a result, the use of a computer‐aided simulation is most often the best way to achieve these goals; however, an appropriate initial value and a systematic approach are necessary for the simulation results to rapidly converge. These objectives can be accomplished with a minimum of trial and error through the following techniques. First, signal gain variations are reduced over a wide bandwidth using a proper pre‐matching network. Then, the source and load impedances are satisfactorily obtained from small‐signal and load‐pull simulations, respectively. Finally, two high‐order Chebyshev low‐pass filters are employed to provide optimum input and output impedance matching networks over a bandwidth of 100 MHz–500 MHz. By using an EM simulation for the substrate, the simulation results were observed to be in close agreement with the measured results.     

Optical Transmission Fiber Design Evolution

This paper reviews optical fiber design evolution for transmission systems over the past three decades, including both multimode and single-modes fibers. Key fiber attributes related to fiber transmission systems and how fiber designs have evolved to improve these attributes to enable higher and higher transmission data rate are discussed. Major fiber design change milestones in the past are covered. Also discussed are recent new developments in optical fiber technology.     

频分多路光纤传输系统的设计考虑

本文详细讨论了频分多路模拟光纤传输系统中的调制方式、光源噪声及非线性特性、接收机前端等对系统性能的影响及设计考虑.     

级联PSA非零色散位移光纤通信系统传输性能的研究

本文通过计算机系统仿真研究了以相敏光放大器（PSA）作为中继光放大器的非零色散位移光纤通信系统的传输性能,分析了PSA系统的码间干扰（ISI）限制距离与信号速率、光纤色散、放大器间距和放大器平均输出信号功率的关系,以及PSA中泵浦光和信号光之间的相位漂移和信号脉冲波形对级联PSA光传输系统传输性能的影响。     

高线性低电压低噪声放大器的设计

研究了一种具有高线性的CMOS低噪声放大器,其工作电压可以低于1V.在这个电路中,加一个工作在线性区的辅助MOS管以提高线性特性.仿真表明这种方法可以提高输入三阶交截点,其代价远小于传统方法为获得1dB线性度改善而必须增加1dB功耗的代价.为了降低该电路中的共栅PMOS管的有载输入阻抗,不使其源极处的电压增益过大而降低电路的线性特性,必须优化其尺寸.仿真使用的模型是TSMC0.18μm射频CMOS工艺库,仿真工具是Cadence的SpectreRF     

一种改进的高功率GaN 放大电路设计方法

传统的功率放大器设计,大都将功率管设计在绝对稳定的状态,再进行匹配电路的设计,这样可以避免振荡的发生,但是同时也会减小放大器的增益,降低1dB压缩点的输出功率。本文提出了一种改进的放大电路设计方法,提出在潜在振荡条件下详细分析振荡区域,准确设计匹配电路,使匹配阻抗避开振荡区域,从而在保证放大器稳定工作的同时,能够提高增益和输出功率。这种方法首次应用于GaN HEMT功率放大器的设计,并且取得了很好的效果。     

高线性低电压低噪声放大器的设计

研究了一种具有高线性的CMOS低噪声放大器,其工作电压可以低于1V.在这个电路中,加一个工作在线性区的辅助MOS管以提高线性特性.仿真表明这种方法可以提高输入三阶交截点,其代价远小于传统方法为获得1dB线性度改善而必须增加1dB功耗的代价.为了降低该电路中的共栅PMOS管的有载输入阻抗,不使其源极处的电压增益过大而降低电路的线性特性,必须优化其尺寸.仿真使用的模型是TSMC 0.18μm射频CMOS工艺库,仿真工具是Cadence的SpectreRF.