An approach to enhance the receiver sensitivity with SOA for optical communication systems

In this paper, we investigate an SOA (semiconductor optical amplifier) preamplifier structure by optimizing the carrier lifetime in order to reduce the amplified spontaneous emission (ASE) noise and crosstalk, with adequate gain increase. This proposed SOA optical preamplifier has no need of optical alignment and antireflection coating. This structure of SOA eliminates the need of optical filter, and exhibits large tolerance to the input light wavelength. The receiver sensitivity is investigated for single and multi channel transmission links. The received power of − 50.34 dBm is observed at bit error rate (BER) 10^− 12 for 10 Gb/s with PIN receiver. Further, the impact of gain, amplified spontaneous emission power and gain variation for different carrier lifetime with input power for OOK system is illustrated. The proposed SOA has constant gain of 30.06 dB up to gain saturation for carrier lifetime 0.18 ns. It is predicted that low value of carrier lifetime suffers less from ASE noise.     

多扇区天线阵列中的微带开关设计与实现

在宽带无线网络中,为了扩展传输距离和提升链路速率,天线系统的性能至关重要。提出了一种应用于多扇区天线阵列中的单刀八掷微带开关,工作频段为5．7-5．9GHz,多扇区天线阵列共包括八个扇区,每个扇区天线水平面波束覆盖范围为45°,信号通过单刀八掷微带开关在各扇区天线间进行高速波束动态切换,从而在满足高增益的同时实现了水平360°全向覆盖。单刀八掷微带开关由微带线和PIN二极管构成,通过采用ADSMomentum电磁场仿真工具进行仿真及实际生产并进行测试,结果表明所设计的单刀八掷微带开关的插入损耗、隔离度和驻波比等关键性能指标均达到设计要求。     

A quad-polarization and frequency reconfigurable square ring slot loaded microstrip patch antenna for WLAN applications

In this paper, a novel polarization and frequency reconfigurable microstrip patch antenna which can switch between vertical and horizontal linear polarizations, left hand and right hand circular polarizations at two WLAN frequencies is presented. The orthogonal linear polarizations are achieved by a square microstrip patch antenna fed by two ports on adjacent sides. By introducing corner truncated perturbation on opposite corners of right diagonal of a square patch, orthogonal circular polarizations are achieved. By controlling the bias voltage of two PIN diodes loaded at perturbed corners, a single structure can achieve quad polarization states. Furthermore, by superimposing a square ring slot into the corner truncated square patch and incorporating four PIN diodes into the square ring slot, quad polarization are achieved at dual frequencies. Simulated and measured results indicate that the antenna can achieve quad polarization at two WLAN bands (5.15–5.35 GHz) and (5.75–5.85 GHz). The proposed antenna is simple, has low profile and can be scaled easily for other frequencies.     

PTN技术与应用

首先我们分析了传输网络IP化的必然趋势,然后全面介绍了PTN技术的特点及实现方式,最后我们对PTN设备的平滑应用给出建议.     

有源雷达吸波体加载调控特性研究

从传输线等效电路理论出发,设计了一种基于有源频率选择表面(active frequency selective surface,AFSS)雷达吸波结构,最上一层是表面层,为AFSS 衬底;中间层是AFSS 层,由频率选择表面(frequency selective surface,FSS)和多个PIN 二极管组成;第三层为泡沫材料组成的介质层。由反射率测量结果表明,改变加载到PIN 二极管两端的直流电压可以控制其反射特性,实现吸波效果灵活可调。另外,利用正弦波作为加载信号也可实现动态地调控;当正弦波频率分别为100kHz、1MHz 和5MHz 时,反射率在3.2～5.6 GHz频段内可获得优于-10dB 的吸波效果。     

凸台式PIN二极管失效分析和键合工艺改进

PIN二极管在封装、试验过程中分别出现大量的失效,分析发现,这种PIN二极管考虑到频率和寄生电容的要求,采用一种凸台式结构,即结区和阳极在一个突出的凸台上,凸台直径仅有28μm。这种凸台边缘只要受到一个较小的机械应力的作用,就会造成凸台崩损、结被破坏,导致结漏电或在小电压下击穿。因此凸台对键合时产生的机械应力很敏感,普通的芯片键合技术也会对凸台造成机械损伤,严重影响器件良品率和长期可靠性。通过对劈刀的改进和重新选择键合丝以及精心调试的键合参数,有效防止了键合对二极管造成的损伤,提高了二极管的成品率和可靠性。     

Characteristics of 6H-silicon carbide PIN diodes prototyping by laser doping

Silicon carbide PIN diodes have been fabricated using a direct-write laser-doping technique that reduces defect generation compared to the conventional ion-implantation technique. Nitrogen and aluminum were successfully incorporated into SiC as n-type and p-type dopants, respectively. Rutherford backscattering studies were conducted to compare the lattice defect generation by the laser-doping and ion-implantation techniques. No amorphization was observed in laser-doped samples, eliminating the need for high-temperature annealing. The current-voltage (I-V) and capacitance-voltage (C-V) characteristics of the PIN diodes were also investigated. The silicon carbide diodes are intended for high-temperature and high-voltage power electronics applications.     

用改进的遗传算法提取PIN光探测器模型参数

光探测器是光电集成电路接收机的重要组成部分,成功提取光电探测器等效模型电路的参数将会对光电集成的研究起到重要作用.将改进的遗传算法用于PIN光探测器小信号等效电路模型参数的提取和优化中,实现PIN光探测器S21、S22参数的测量值与模拟值拟合.改进后的遗传算法自动优化了遗传、杂交和变异算子,节省了寻找最佳遗传、杂交和变异概率的时间,提高了参数提取的速度.     

波导二极管移相器的设计

介绍了波导二极管移相器的设计原理和实现方法。运用矩形波导的传输理论,将加载线型移相单元插入矩形波导内,对波导内的24个加载线型移相单元进行调配组合实现五位地址数码控制移相器。实测结果表明该移相器移相范围大、插入损耗低、输入驻波小、转换时间快、移相精度高及耐高功率性好。     

自由光通信中PIN探测器光阈值特性研究

研究自由光通信中PIN探测器在1 064 nm波长下的阈值特性。为了观察PIN光电探测器的激光损伤阈值对光通信的影响,利用Nd:YAG激光器、衰减器、示波器和PIN探测器等仪器模拟无线空间光通信系统。实验以PIN探测器在1 064 nm波段为样本。通过调整衰减器的衰减系数,从而观察探测器达到强光饱和时通信波形的眼图变化,判断探测器是否能够继续通信。通过实验发现:探测器达到深度饱和时,系统通信出现脉宽展宽现象,并出现严重的码间串扰无法满足通信指标。通过实验阈值,建立空间数学模型。观察距离、束散角和辐照夹角对致盲激光器功率的影响。