Towards 640 Gbit/s wavelength conversion based on nonlinear polarization rotation in a semiconductor optical amplifier

Taking into account ultra-fast carrier dynamics, this paper models 640 Gbit/s wavelength conversion scheme based on nonlinear polarization rotation （NPR） in a single semiconductor optical amplifier （SOA） and investigates the performance of this kind of wavelength conversion scheme in detail. In this model, two carrier temperature equations are introduced to substitute two energy density equations, which reduce the complexity of calculation in comparison with the previous model. The temporary gain and phase shift dynamics induced by ultra-short optical pulses are numerically simulated and the simulated results are qualitatively in good agreement with reported experimental results. Simulated results show that non-inverted and inverted 640 Gbit/s wavelength conversions based on NPR are achieved with clear open eye diagrams. To further investigate the performance of the non-inverted wavelength conversion scheme, the dependence of output extinction ratio （ER） on some key parameters used in simulation is illustrated. Furthermore, simulated analyses show that high performance non-inverted wavelength conversion based on NPR can be achieved by using a red-shifted filtering scheme.

Influence of double Rayleigh backscatter in CATV systems with Raman amplifiers

The double Rayleigh backscatter （DRB） effect in long distance CATV systems using fiber Raman amplifiers （FRAs） is investigated theoretically in the paper. As a comparison, performance of a system with erbium doped fiber amplifier （EDFA） is also evaluated. According to the simulation results, it is found that, in case of FRA, the increase of carrier-to-noise ratio （CNR） due to the DRB effect will not impair the performance more than that using EDFA.

Robust Digital Control of a Broadband PWM Power Amplifier

Lately, it is required that the bandwidth of PWM （pulse width modulation） power amplifier is extended. For example, it is in application of the testing power supply of a low frequency immunity examination, or a class-D amplifier. In this paper, the authors show that the bandwidth of PWM power amplifier can be controller. This controller is implemented on a DSP （digital can be made wider with this controller. extended by using an approximate 2DOF （2-degree-of-freedom） digital signal processor）. It is demonstrated from experiments that the bandwidth

Non-Overlapping Conditions to Enable Multi- Dimensional Behavioral Models/DPDs for Multi-Band or Non-Continuous Carrier Aggregation Systems

To linearize the multi.band PAs/transmitters, a serial of multi.band predistortion models based on multi.dimensional architecture have been proposed. However, most of these models work properly only for the signals whose harmonic and intermodulation products of carriers' non.overlap with the interested fundamental bands. In this paper, the non.overlapping conditions for dual.band and tri.band signals are derived and denoted in the form of closed.form expression. It can be used to verify whether a given dual.band/multi.band signals can be linearized properly by these multi.dimensional behavioral models. Also the conditions can be used to plan the frequency spacing and maximum bandwidth of a multi.band or non.continuous carrier aggregation signal. Several dual.band and triband signals were tested on the same PA, by employing 2.D DPD and 3.D DPD behavioral models. The measurement results show that the signals which don't satisfy the non.overlapping conditions cannot be linearized well by the multi.dimensional behavioral models which does not take the harmonic and intermodulation products of carriers' into account.

L波段F类高效率载片式功率放大器设计

为解决传统F类功率放大器受晶体管输出电容和输出电感影响,导致调谐匹配网络结构复杂的问题,提出了一种紧凑型的输出调谐匹配电路结构。通过分析基波匹配电路的阻抗特性,在谐波频率处可将其等效为一段有限的到地电抗。在设计谐波匹配电路时,将该电抗元件与谐波匹配电路进行协同设计,避免引入多余的元件来消除基波匹配网络对谐波匹配网络的影响,减小了功放的整体面积。最后,仅引入一个LC串联谐振网络,实现对输出二次\\三次谐波的控制以提高输出效率。基于该电路结构,采用0.25μm GaN HEMT管芯设计了一款L波段高效率功率放大器,并且使用内匹配技术在7 mm×8 mm铜-钼-铜载片上实现。实测结果表明,在漏源电压28 V、10%占空比的脉冲输入的工作条件下,该功率放大器在1.18~1.42 GHz频带内实现饱和输出功率48.1~48.4 dBm,功率附加效率61%~63%,功率增益大于26 dB。该结构在提高效率的同时,降低了电路复杂度。

非对称级联多电平功率放大器的虚拟载波移相PWM调制策略

由N个相同H桥功率模块(H-bridge power module,HBPM)组成的传统级联H桥功率放大器(cascaded H-bridge power amplifier,CHB-PA)最多可输出2N+1的电平数,输出电平数直接影响功率放大器的正弦特性和保真性能。在级联HBPM数量相同的情况下,首先提出了一种非对称级联多电平功率放大器(asymmetrical cascaded multilevel power amplifier,ACM-PA);其次,为了与传统CHB-PA有相同HBPM数目的ACM-PA,提出一种虚拟载波移相脉宽调制(virtual carrier phase shift pulse width modulation,VCPS-PWM)策略,将输出电平数提高到6N-3;最后,通过仿真对比验证了所提出的ACM-PA和VCPS-PWM可以显著提高输出电平数,降低负载电流的总谐波失真,提高功率放大器的保真性能。

Cross-linked lipoic acid nanocapsules serve as H_(2)O_(2) amplifier to strengthen the H_(2)O_(2)-sensitive prodrug activation

The H_(2)O_(2) -triggered prodrug activation represents a hot topic while the low H_(2)O_(2) level of cancer cells hindered the complete activation of parent drugs and resulted in the poor therapeutic effect. Here, we developed an H_(2)O_(2) amplifier fabricated by crosslinked lipoic acid nanocapsules(cLANCs), which would selectively elevate the intracellular H_(2)O_(2) level of cancer cells 3.4-fold higher than that of untreated cancer cells so as to speed up the activation of parent drug from the loaded prodrugs(Pro-5-FU). The cytotoxicity showed that the killing effect of Pro-5-FU loaded in cLANCs(Pro-5-FU@cLANCs) arrived up to 1.6-time higher than that of Pro-5-FU alone against A549 cells, and was even close to free 5-FU. The in vivo anticancer evaluation gave the tumor inhibition rate(TIR) and survival rate(SR) of Pro-5-FU@cLANCs against A549 tumor-bearing nude mice up to 73.1% and 80%,respectively, much higher than those of Pro-5-FU(TIR: 41.2%, SR: 20%) or free 5-FU(TIR: 50.6%, SR: 0%). This nanodrug constructed the first example that utilizes the drug carriers as H_(2)O_(2) amplifier to strengthen the prodrug activation.

A high efficiency PWM CMOS class-D audio power amplifier

Based on the difference close-loop feedback technique and the difference pre-amp, a high efficiency PWM CMOS class-D audio power amplifier is proposed. A rail-to-rail PWM comparator with window function has been embedded in the class-D audio power amplifier. Design results based on the CSMC 0.5μm CMOS process show that the max efficiency is 90%, the PSRR is -75 dB, the power supply voltage range is 2.5-5.5 V, the THD＋N in 1 kHz input frequency is less than 0.20%, the quiescent current in no load is 2.8 mA, and the shutdown current is 0.5 pA, The active area of the class-D audio power amplifier is about 1.47 × 1.52 mm^2. With the good performance, the class-D audio power amplifier can be applied to several audio power systems.

矿用重型支架搬运车全液压转向系统应用研究

介绍了重型支架搬运车总体结构及转向实现形式,对采用双液压缸转向的转向装置排量进行了理论计算分析。比较单级与两级液压转向的特点,得出在重型支架搬运车上采用两级液压转向的可行性。详细阐述并分析了先导控制转向阀式两级液压转向系统和先导控制流量放大器式两级液压转向系统的功能及元件选型注意事项。结合整机液压系统构成与功能,完成了40 t铲板式支架搬运车先导控制转向阀式两级液压转向系统设计与关键元部件选型,经现场应用验证,该系统转向操纵力小、转向灵活,满足了使用要求,为类似系统设计提供了借鉴。

5G移动通信网络智能节能应用方案

文章通过对鄂尔多斯市5G移动通信网络设备的能源消耗分析,根据网络选定区域内小区的历史业务数据,构建基站业务负荷预测模型,分别应用“符号关断”“RF智能关断”“载波关断”这三项节能措施,持续挖掘无线设备级节能功能的技术与方案,进一步优化节能参数,降低全网基站功耗,达到降本增效的目的。

Multimode high-resolution DPWM for RF class-D amplifiers

This paper describes a multimode high-resolution digital pulse width modulator.This modulator,based on a novel hybrid structure,not only has a programmable duty cycle but also realizes phase modulation.A 576 ps pulse resolution is achieved based on a 13.56 MHz switching frequency for near field communication.Fabricated in a SMIC 0.18-μm EEPROM CMOS process,the total area of modulator is only 130×180μm2.Measurement results validate the multi-mode modulation function and high pulse resolution.

硅基光参量放大器的增益和噪声特性研究

为了研究硅基光参量放大器(OPA)更好的增益和噪声特性,在研究硅基光参量放大器(OPA)中拉曼效应及其噪声理论的基础上,用数值仿真研究了硅基OPA中泵浦峰值功率、泵浦宽度、脉冲重复率、自由载流子寿命对其增益和NF特性产生的影响。结果表明,当泵浦功率大于2 W后,由于TPA与FCA的非线性损伤的存在使得增益逐渐降低,即在硅基OPA中高峰值泵浦功率并不意味着大的增益。短脉冲宽度更易获得净增益,低的脉冲重复率下NF更小。当泵浦脉冲重复率为10 GHz,泵浦脉冲宽度为2.5 ps时,自由载流子的寿命只要低于500 ps就可以获得净增益。

Carrier-envelope phase passively stabilized near-infrared laser pulses from a dual-frequency pumped noncollinear optical parametric amplifier

By inversing the signal and idler in a two-stage noncollinear optical parametric amplifier which is,respectively,pumped by the second harmonic and fundamental wave of femtosecond Ti:sapphire laser at repetition rate of1 kHz,the carrier-envelope phase(CEP)passively stabilized pulses with a tunable wavelength from 1.1 to 1.6 lm are obtained with maximum energy of 95 lJ at 1.3 lm under the pump energy of 500 lJ.The CEP jitter of pulses is 108 mrad measured by an f-2f interferometer.This work demonstrates a new way to efficiently generate tunable near-infrared femtosecond laser pulses with self-stabilized CEP.

使用掺铒光纤放大器的光纤CATV系统载噪比的研究

本文全面分析了加入掺铒光纤放大器的ＣＡＴＶ系统噪音。

基于半导体光放大器的可扩展型光开关矩阵

未来的高速和高度灵活的光分组交换网络要求开关速度达到纳秒量级且集成度高的大规模空间光开关矩阵。在分析了基于半导体光放大器的常用结构形式的光开关矩阵存在规模局限性的基础上 ,综述了新型的可实现大规模集成的基于半导体光放大器的光开关矩阵的基本原理和研究现状。

半导体激光放大器对超短光脉冲串的动态响应

本文利用速率方程从理论上研究了行波式半导体激光放大器(TWA)对来自主动锁模半导体激光器的皮秒脉冲串的动态响应,计算了脉冲串的动态增益、TWA的载流子的时间空间变化,本文首次使用光脉冲光子数(对应于脉冲能量)表示法研究TWA,动态增益饱和只与脉冲光子数有关,与输入功率无关,此外讨论了一些全光通信系统中与TWA有关的问题。

半导体光放大器对超短光脉冲放大过程中载流子寿命的变化

修正了人们在研究半导体光放大器对光脉冲的放大这一动态过程中把载流子寿命取为常数这一处理方法 .通过考虑放大器中载流子的实际复合机制 ,提出了一个可研究载流子寿命变化的模型 .数值计算的结果表明 ,在半导体光放大器对超短光脉冲进行放大这一动态过程中 ,载流子寿命变化明显 。

自行式框架车液压控制系统的研究

简述了自行式框架车液压控制系统的设计思路,分析了自行式框架车驱动液压系统、悬挂液压系统以及转向液压系统的工作原理,详细介绍了自行式框架车由液压负荷传感转向器和流量放大器组成的新型全液压转向系统,并对该转向系统的优点进行了分析.

关于自适应预失真射频功率放大器线性化研究

介绍新的带外信号检测方法和自适应模拟预失真线性化技术,并应用于CDMA直放站的5W自适应射频线性功率放大器。为了有效抑制临信道频谱再生,通过自适应检测和自适应预失真控制使输出信号的3阶和5阶交调失真分别改善8dBc和6dBc。

两总线智能化气体检测系统

根据提供的两总线智能化的气体检测系统的工作原理及设计方法 ,所制成的探测器采用催化燃烧式传感器的特点 :是以棒调节零点和增益 ;通讯采用直流电源载波方法 ;信号线与电源线公用。由此 ,不仅降低了布线成本 ,而且提高了系统可靠性。