Stable 100-Gb/s POLMUX-DQPSK Transmission With Automatic Polarization Stabilization

The reliability of 100-Gb/s polarization-multiplexed return-to-zero differential quadrature phase-shift keying transmission is demonstrated exploiting direct detection and automatic polarization stabilization. We experimentally verified a 2-dB chromatic dispersion tolerance of 100 ps/nm. Long-term stability has also been assessed by sampling the bit-error rate every 3 min over a continuous period of 8 h. Measurements are performed both in back-to-back and after 8.8-km uncompensated standard single-mode fiber, in the presence of a polarization scrambler.      

偏振模色散对200 Gbit/s零路径色散控制光纤链系统的影响

基于一种二阶和三阶色散都作了完全补偿 (路径平均色散为零 )的光纤级联系统模型 ,用数值法研究了偏振模色散对皮秒光脉冲传输的影响。在零路径色散补偿系统中 ,线性色散得以完全补偿 ,为了减小非线性效应引起的脉冲窄化 ,系统必须保持较小的功率 ,但这样会影响系统的信噪比。计算结果表明 ,偏振模色散与非线性效应相互平衡 ,可使系统在较高的功率下保持脉冲宽度基本不变 ,从而获得较好的传输性能     

Nonlinear Polarization Rotation in Semiconductor Optical Amplifiers With Linear Polarization Maintenance

We propose a geometrical model based on the concept of dynamic eigenstates of polarization to describe the behavior of nonlinear polarization rotation (NPR) arising in semiconductor optical amplifiers (SOAs). The rotation axis with respect to either the bias current or the optical power variation is demonstrated on the Poincare sphere (PS), meanwhile a procedure to find the rotation axis is presented. Thus, the SOA-based NPR with linear polarization maintenance (zero polarization ellipticity angle) can be achieved experimentally. The rotation of polarization azimuth on the PS with respect to the bias current, the probe signal power, and the pump signal power variation is measured experimentally. The 180deg phase difference between the transverse electric and the transverse magnetic modes can be all achieved with linear polarization maintenance.     

一种在光纤通信中的偏振稳定系统设计与实现

针对光信号在非保偏环境下传输偏振态随机变化的现象,设计了一种可实时保持信号偏振态稳定的系统,用于光纤通信系统接收端。该偏振稳定系统采用基于偏振跟踪的直接检测方案,使用功率差作为反馈变量,无需高速电路支撑。反馈控制算法采用禁忌-粒子群优化算法,将粒子群算法自适应化并引入禁忌表,形成收敛速度快、不易陷入局部最优值的优质算法。系统硬件实现后,经实验验证了该偏振稳定系统的有效性,且对光信号的调制速率、调制格式透明。     

Bidirectional Optical Interconnection at Gb/s Data Rates With Monolithically Integrated VCSEL-MSM Transceiver Chips

We present the operation characteristics of 850-nm wavelength GaAs-based monolithically integrated transceiver chips designed for low-cost short-distance bidirectional optical data transmission over a butt-coupled 200-mum core diameter polymer-clad silica fiber. The chips containing a vertical-cavity surface-emitting laser and a large-area metal-semiconductor-metal photodiode can well handle data rates of 2.5Gb/s in back-to-back mode and 0.5 Gb/s for 10-m fiber length     

Direct Detection of 107-Gb/s Polarization-Multiplexed RZ-DQPSK Without Optical Polarization Demultiplexing

We demonstrate a direct detection scheme for a 107-Gb/s polarization-multiplexed return-to-zero differential quadrature phase-shift keyed signal, featuring automatic polarization demultiplexing without polarization tracking. The technique is used to study the performance under various impairments, including tight optical filtering, polarization-mode dispersion, and single-channel transmission in a dispersion-managed optical link. The performance is also compared with optical polarization demultiplexing.      

38-krad/s 3.8-Grad Broadband Endless Optical Polarization Tracking Using LiNbO$_{3}$ Device

We demonstrate automatic endless optical polarization tracking over 3.8 Grad at up to 38-krad/s control speed with mean/maximum polarization errors of 0.068/0.185 rad. Without polarization fluctuations, mean/maximum polarization errors are 0.05/0.1 rad. Small-signal control time constant is about 2 $mu$s. Function is maintained over the wavelength range 1505–1570 nm.      

10Gbit／s光纤通信系统偏振模色散动态补偿技术

分别用固定长度保偏光纤和可变光延迟线实现偏振模色散(PMD)补偿的实验。从理论和实验上分析了射频电功率随差分群延迟(DGD)的变化，实验给出了两种补偿方案的补偿前后的眼图。对固定补偿和动态补偿各自的特点进行了分析比较。固定补偿的速度很快，但补偿的精度不够高；而用光可变延迟线的补偿可以实现动态补偿并且补偿精度高，但有时响应时间较长。     

Optical Stabilization of Waveguide Amplifiers for WDM Ring Network With Recirculating Optical Power

We demonstrate an all-optical wavelength-division-multiplexing ring network immune to transients based on individual optically gain clamped waveguide amplifiers. The ring network is compared to a similar point-to-point configuration to quantify the effect of recirculating amplifier noise. In the results, we notice that the optical stabilization is strong enough to overcome the effect of accumulated amplifier noise over the entire transmission bandwidth, and no lasing or chaotic behavior occurs. In addition, due to the independent amplifier stabilization, the network has shown to be robust even in the case of failure and restoration. We prove that the obtained results are scalable with the amplifier number. All results are also applicable to fiber-based amplifiers.     

Optical Fiber System Trials at 8 Mbits/s and 140 Mbits/s

This paper describes an optical fiber system developed at the British Post Office (BPO) Research Centre, Martlesham Heath, which provides telephone circuits in an 8 Mbit/s junction between the Centre and Ipswich Telephone Exchange via 13 km of BICC cable incorporating Corning fibers. In parallel, a 140 Mbit/s system operating over 8 km of cable has been demonstrated. The systems were constructed in accordance with standard BPO equipment practice and the cables were installed by local area staff in existing ducts.     

Optimum Receiver Filters for Optical Fiber Systems With Polarization Mode Dispersion

We use a semi-analytical receiver model combined with importance sampling applied to first-order polarization-mode dispersion (PMD) to show that the performance of optical fiber systems whose optical and electrical receiver filter bandwidths are optimized for polarization-mode dispersion in practical on-off-keyed systems is equivalent to the performance of the same systems in which the receiver filters are optimized for operation in the absence of PMD. We also observed an increase in the sensitivity of the performance with respect to variations in the receiver filter bandwidths in the return-to-zero format in systems with PMD when compared with PMD-free operation.      

Micromachined Polarization Beam Splitter With Adjustable Leak Ratio for Optical Pickup

In this letter, we propose the optomechanical design and fabrication of a novel batched-processed polarization beam splitter (PBS) with an adjustable leak ratio for optical recording applications. The micro-PBS was fabricated by a 410-nm low stress silicon nitride Si₃N₄ membrane integrated with a bimorph actuator. A dc drive voltage was applied to allow an adjustable leak ratio (0-0.24) with incident angle from 65deg to 75deg for operation in the different optical requirements (phase-change and magneto-optical disks) at lambda = 633 nm. The characteristics of the fabricated PBS are in close agreement with the theoretical calculations and confirm its feasibility.     

Beyond 240 Gb/s per Wavelength Optical Transmission Using Coded Hybrid Subcarrier/Amplitude/Phase/Polarization Modulation

In this letter, we propose a low-density parity-check coded hybrid subcarrier/amplitude/phase/polarization (H-SAPP) modulation scheme suitable to achieve a 240-Gb/s single-channel transmission rate over optical channels. The proposed scheme doubles the aggregate transmission rate achievable by eight-quadrature amplitude modulation while providing 2-dB optical signal-to-noise ratio performance improvement at a bit-error-ratio (BER) of $10^{-6}$ . Moreover, H-SAPP can increase the aggregate rate of the hybrid amplitude/phase/polarization scheme while maintaining the BER performance intact.      

Optical phase-locked PSK heterodyne experiment at 4 Gb/s

A 4 Gb/s phase-locked optical PSK (phase shift keying) heterodyne communication system is demonstrated. The receiver was implemented with a single 100-Ω loaded p-i-n photodiode and a 1320-nm diode-pumped miniature Nd:YAG laser as a local oscillator. For a 2⁷-1 PRBS (pseudorandom bit sequence), the receiver sensitivity was -34.2 dBm or 631 photons/bit. The corresponding power on the surface of the detector was -37.3 dBm or 309 photons/bit. With a 2¹⁵-1 PRBS, a 2.6 dB additional sensitivity degradation was observed due to the nonideal frequency response of the phase modulator and the receiver amplifiers     

40/100Gb/s偏振复用相干检测光模块的技术分析

利用偏振复用四相相移键控(PM-QPSK)调制技术和相干检测技术,实现40/100 Gb/s光模块的长距离传输。基于相干检测的偏振复用四相相移键控调制格式是40/100 Gb/s长距离传输的主要研究方向,与直接检测系统相比,相干检测具有更高的频谱效率。现有的相干检测是基于高速模数转换器(ADC)的快速发展,ADC对混频后的基带信号采样,通过数字信号处理(DSP)芯片数字均衡的方式完成相干接收。数字信号处理芯片数字均衡的方式可以实现定时恢复、信号恢复、偏振和偏振模色散(PMD)跟踪,以及色散补偿。     

107-Gb/s Serial Optical Packet Switching With 1-bit/s/Hz Spectral Efficiency for 100-GbE Backplanes

We demonstrate 107-Gb/s optical packet switching using electronically multiplexed duobinary signals, fast tunable lasers, and a 40 times 40 arrayed waveguide grating router. With a spectral efficiency of 1 bit/s/Hz, the fabric scales to 4-Tb/s capacity and is suitable for 100-Gb Ethernet backplanes.     

Optical time-division multiplexed transmission system experiment at 8 Gbit/s

We describe the design and performance of an experimental two-channel optical time-division multiplexed fibre transmission system operating at a wavelength of 1.3 ?m and a bit rate of 8 Gbit/s. Transmission over 8 km of single-mode fibre with low crosstalk and transmission error rates as low as 10?10 is demonstrated.     

Demonstration of Deflection Routing With Layer-2 Evaluation at 40 Gb/s in a Three-Node Optical Burst Switching Testbed

We developed an optical burst switching (OBS) network testbed with three nodes, where each node consisted of a fast 5 5 (Pb,La)(Zr,Ti)O optical matrix switch. A newly developed Ether frame media converter was successfully used to evaluate Layer-2 performance of the testbed, with a line rate of 40Gb/s. A dynamic deflection routing scheme for contention resolution is implemented. Error-free switching with 40-Gb/s payload was achieved over the three nodes, promising low frame loss due to dynamic operation. By comparing effects of random collision with and without deflection routing for varying loads, we demonstrate that near-theoretical low frame loss is achievable in fast Layer-2 (Ether frame) transport over OBS networks.     

Investigation of 43-Gb/s Transmission With a Wavelength Preserving SOA-Based Optical Regenerator

Transmission with cascaded optical regeneration based on synchronous modulation combined with optical reshaping by cross-gain compression in a semiconductor optical amplifier is investigated at 43 Gb/s over transoceanic distances (10 000 km). The proposed optical regenerator configuration performs signal reshaping and retiming while preserving the input signal wavelength. The regenerator cascadability properties are investigated using a reconfigurable loop to assess the impact of different inter-regeneration spacing on the transmission signal properties.      

具有连续自动温度补偿功能的10Gb/s光收发模块

设计并制作了一种10Gb/s光收发模块,在宽温度范围内能够保持稳定的光功率和消光比。基于背电流和光功率的换算比例,计算其偏置电流修正值和调制电流修正值,实现了光模块运行过程中激光器的工作参数可自动连续调节。通过高速电路信号仿真设计,解决了信号完整性、串扰和电磁兼容等问题。光模块收发通道可以独立工作,传输速率可达10Gb/s,实现了光模块高速率、高稳定性以及小体积设计,为甚短距离高速数据传输和处理提供了高可靠性的数据链接。