Mitigation of signal quality degradation induced by PMD using synchronous modulation

In-line synchronous modulation as a way of mitigating the signal quality degradation induced by polar ization mode dispersion(PMD)was experimentally studied using 10-Gb/s return to zero signal.Bit error rate of the degraded signal and the synchronously modulated signal under the differential group delay(DGD)values of 10,20,34,and 70 ps was measured and compared.The experimental results showed that in-line synchronous modulation is useful to mitigate the signal quality degeneration induced by PMD.1-dB power penalty reduction was obtained even when the PMD was as high as 70％ of the bit interval.The limitation of method is also discussed.     

Dynamic PMD compensation in 40-Gb/s optical communication system

A 40-Gb/s optical time division multiplexing (OTDM) return-to-zero (RZ) transmission experiments including a dynamic polarization mode dispersion (PMD) compensation was reported. The dynamic PMD compensator is made up of two-stage four degrees of freedom (DOF). The first stage adopts polarization controller and fixed time-delayed line. The second stage is variable differential group delay (DGD) element. The PMD monitoring technique is based on degree of polarization (DOP) as error signal. A novel practical adaptive optimization algorithm was introduced in dynamic adaptive PMD compensation. The experimental results show that the performance of the PMD compensator is excellent for 40-Gb/s RZ transmission systems with the large DGD. With this compensator, a significant improvement of system performance can be achieved in the eye pattern of a received signal. The first-order compensating ability of the compensator is greater than 30 ps. The second-order compensating ability is greater than 200 ps2. The first     

CW Nd:YAG THERMO-STABLE RESONATORS OPERATING IN POWER-STEADY STATES

There are two dynamical stable zones in the operation of solid laser containing a thermal lens. In this paper, we point out that in the two stable zones two kinds of dynamical stable states can exist in a laser resonator: mode-steady thermo-stable state and power-steady thermo-stable state. They are different from each other in general. The operating conditions for power-steady thermo-stable state are presented. A cw Nd: YAG thermo-stable resonator operating in power-steady states has been designed, and 40 W TEM₀₀ output power in 1.06μm is obtained experimentally.     

低温辐射计测量系统中的光路调整

低温辐射计是目前光辐射测量不确定度最低的仪器。测量不确定度主要依赖于光路的调整和实验环境条件的控制。本文介绍了用低温辐射计测量激光功率的实验装置和调节方法 ,并提出了一种用直角棱镜观察、调节低温辐射计的新方法     

光纤激光功率溯源至低温辐射计方法

介绍了1.3 μm/1.5 μm光纤激光功率溯源至低温辐射计的测量方法,与传统溯源至绝对辐射计的方法相比较,最终利用低温辐射计法通过633 nm波长稳定光源标定陷阱式探测器,然后用陷阱式探测器将量值传递到陷阱式量传探测器,最后通过1310 nm/1550 nm通信用光功率稳定光源通过热释电光功率计标定InGaAs光电探测器并用于测量光纤功率。实验结果表明,溯源至低温辐射计的光纤功率测量方法在1310 nm及1550 nm波长点处对一标准光功率计修正系数测量的相对标准差分别为0.0011及0.0007,其测量不确定度可优于0.6％(k=2),在保证量值一致性的同时有效降低了测量不确定度,提高量值传递精度。     

4×10Gb/s OTDM系统中偏振模色散自适应补偿的研究

利用信号偏振度为反馈信号，基于可变步长最大值搜索算法实现了4×10?Gb/s 光时分复用 （OTDM）系统偏振模色散（PMD）自适应跟踪补偿实验.PMD补偿器为偏振控制器加可变时延 线的四自由度结构.最大差分群时延（DGD）补偿量为25?ps，即信号的一个比特周期，补偿 时间小于50?ms. 关键词： 偏振模色散 光时分复用系统 偏振度 自适应补偿     

一种可编程PMD模拟器

为了研究光纤通信中的偏振模色散(PMD)及其对高速光通信系统的影响和补偿技术,研制了一种可编程控制的PMD模拟器,它由6组双折射晶体和磁光晶体组成,群时延差(DGD)变化范围为±(0.3~35) ps,可设为不同平均值的Maxwell统计分布随机变化,也可以设为其它要求的数学分布.实验证明,该模拟器测量值与理论符合得很好,且具有较高的重复性和稳定性,响应时间小于1 ms.这种模拟器可用于10 Gb/s和40 Gb/s光传输系统PMD问题的研究.     

Mitigation of signal quality degradation induced by PMD using synchronous modulation

In-line synchronous modulation as a way of mitigating the signal quality degradation induced by polarization mode dispersion (PMD) was experimentally studied using 10-Gb/s return to zero signal. Bit error rate of the degraded signal and the synchronously modulated signal under the differential group delay (DGD) values of 10, 20, 34, and 70 ps was measured and compared. The experimental results showed that in-line synchronous modulation is useful to mitigate the signal quality degeneration induced by PMD. 1-dB power penalty reduction was obtained even when the PMD was as high as 70% of the bit interval. The limitation of method is also discussed.