Packet labeling technique using electronic code-division multiple-access for WDM packet-based access networks

We propose and experimentally demonstrate the feasibility of a packet labeling technique using electronic code-division multiple-access for a wavelength-division-multiplexing (WDM) packet-based access network, whereby each wavelength is assigned a unique electronic code-based label on a radio-frequency subcarrier. Such a technique allows individual wavelength channels to be electronically identified without requiring the use of a WDM demultiplexer. We experimentally demonstrate this technique with two WDM channels each with 1.25-Gb/s payload data and 10-Mb/s header coded onto an electronic code at 160 Mb/s. The experimental results and theoretical analysis show that this technique has the potential to support large numbers of WDM channels.     

10 Gbit/s four-channel wavelength- and polarisation-divisionmultiplexing transmission over 340 km with 0.5 nm channel spacing

The authors propose a novel WDM transmission technique combined with polarisation-division multiplexing (PDM) which doubles the frequency utilisation efficiency. This technique is used to transmit a 10 Gbit/s four-channel WDM signal with 0.5 nm channel spacing over 340 km and the signal is demultiplexed using an optical filter having 0.5 nm FWHM and a polarisation beamsplitter     

Time-domain interleaving technique for wavelength-swept light based super dense WDM transmitter

Proposed is a time-domain interleaving technique for increasing the transmission rate of a previously reported wavelength-swept light based WDM transmitter. With this technique, the bit rate of each channel can be multiplied without increasing the repetition frequency of the wavelength sweep and without severe inter-channel crosstalk. A four-channel 2.5 Gbit/s super dense WDM transmission experiment with two interleaved 1.25 Gbit/s data streams is demonstrated.     

Long-haul soliton WDM transmission with periodic dispersioncompensation and dispersion slope compensation

A 20 Gb/s-based soliton wavelength division multiplexed (WDM) transmission experiments using periodic dispersion compensation and dispersion slope compensation were demonstrated. Accumulated dispersion slope was compensated with two methods. The first method was periodical individual dispersion compensation. By using this technique, 60 Gb/s (20 Gb/s×3 WDM) transmission over 8000 km was demonstrated. The second method was the use of a dispersion-flattened transmission fiber. 160 Gb/s (20 Gb/s×8 WDM) transmission over 4000 km using periodically dispersion compensated dispersion-flattened fiber was also demonstrated     

New techniques for the suppression of the four-wave mixing-induced distortion in nonzero dispersion fiber WDM systems

The performance of a wavelength-division multiplexing (WDM) optical network can be severely degraded due to fiber nonlinear effects. In the case where nonzero dispersion (NZD) fibers are employed, the four-wave mixing (FWM) effect sets an upper limit on the input power, especially in the case of narrow channel spacing. In order to reduce FWM-induced distortion two new techniques, the hybrid amplitude-/frequency-shift keying (ASK/FSK) modulation and the use of prechirped pulses are investigated. It is shown that both techniques can greatly improve the Q-factor in a 10 Gb/s WDM system. This happens even for very high input powers (/spl sim/10 dBm), where the degradation of the conventional WDM system is prohibitively high. The proposed methods are also applied and tested in higher bit rates (40 Gb/s). It is deduced that although the hybrid ASK/FSK modulation technique marginally improves the system performance, the optical prechirp technique can still be used to greatly increase the maximum allowable input power of the system.     

Transoceanic WDM System with More Than 100 Gb/s Capacity

This paper reviews several key technologies to realize a transoceanic wavelength-division-multiplexing (WDM) system with more than 100 Gb/s capacity. The key technologies include a novel gain equalization scheme, a broadband erbium-doped fiber amplifier, a chromatic dispersion compensation technique at a transmitter, and a RZ modulation format. Employing these new technologies, we successfully demonstrated a 32 channel 5.3 Gb/s (total capacity of 170 Gb/s) WDM signal transmission over 9879 km.     

Design and experimental characterization of EDFA-based WDM ring networks with free ASE light recirculation and link control for network survivability

We theoretically and experimentally investigate the performance of erbium-doped fiber amplifier (EDFA)-based WDM ring networks with free amplified spontaneous emission (ASE) light recirculation. We show that, with proper network and amplifier design, the lasing light generated by free ASE recirculation within the looped network provides an effective gain clamping technique, ensuring limited signal power excursions under WDM channels add-drop operations. Considering a ring network composed of eight fiber sections and eight EDFAs, maximum signal power overshoots below 2.5dB have been measured under 23/24 WDM channels drop. Optical signal-to-noise ratio (OSNR) analysis and bit-error rate (BER) measurement at 10 Gb/s confirm acceptable performances and negligible penalties due to polarization effects and relative intensity noise transfer from laser light to WDM signals. We also propose and demonstrate a new link control technique which overcomes the main limiting factors of such networks, respectively, related to OSNR degradation, stability and survivability to fiber and EDFA breakages.     

Chromatic Dispersion Monitoring Technique Using Pilot Tone Carried by Broadband Light Source

We propose and demonstrate a simple chromatic dispersion monitoring technique based on the pilot tone generated by a broadband light source (BLS). Previously, the pilot tone has been obtained by directly modulating each transmitter laser with a small sinusoidal current. Thus, for use in the wavelength-division- multiplexed (WDM) network, each transmitter should be modulated with a unique pilot tone. However, we obtain the pilot tone by modulating an additional BLS such as a reflective semiconductor optical amplifier. Thus, there is no need to modulate each transmitter laser. We evaluate the performance of the proposed technique in an 8$, times ,$10 Gb/s WDM system. The result shows that, unlike the conventional pilot-tone-based monitoring technique, the performance of this technique is almost insensitive to the polarization-mode dispersion.      

Key technologies for terabit/second WDM systems with high spectralefficiency of over 1 bit/s/Hz

To fully utilize a limited gain bandwidth of about 35 nm (4.4 THz) in an erbium-doped fiber amplifier, an increase in signal spectral efficiency is required. In this paper, we investigate the key technologies to achieve terabit/second wavelength-division multiplexing (WDM) systems with over 1 bit/s/Hz spectral efficiency. Optical duobinary signals, which have narrower optical spectra than conventional intensity modulation signals, were applied to such dense WDM systems. The measured minimum channel spacing for 20-Gbit/s optical duobinary signals was 32 GHz and a spectral efficiency of over 0.6 bit/s/Hz was reached. By using polarization interleave multiplexing, spectral efficiency was expected to reach 1.2 bit/s/Hz in an ideal case with no polarization dependencies along the transmission lines. In such ultradense WDM systems with narrower channel spacing, stabilizing the wavelengths of laser diodes is an important issue for achieving stable operation over long periods. To do this, we developed a simple and flexible wavelength stabilization system which uses a multiwavelength meter. The wavelengths for 116 channels with 35-GHz spacing were stabilized within ±150 MHz. The stabilization system is applicable to ultradense WDM signals with a spectral efficiency of over 1 bit/s/Hz by employing wavelength interleave multiplexing and an optical selector switch. On the basis of these investigations, we demonstrated a 2.6-Tbit/s (20 Gbit/s×132 channels) WDM transmission by using optical duobinary signals. In addition, 1.28-Tbit/s (20 Gbit/s×64 channels) WDM transmission with a high spectral efficiency of 1 bit/s/Hz was achieved by using polarization interleave multiplexing     

All-optical multiwavelength clock recovery using integratedsemiconductor amplifier array module

Simultaneous all-optical clock-recovery of WDM channels at 10 Gbit/s is demonstrated in an actively-modelocked fibre ring laser configuration using a novel 22-channel semiconductor optical amplifier array module integrated with two waveguide grating routers. The technique is based on using adjacent free-spectral ranges for the incoming data and recovered clock     

新型副载波调制EDFA远程在线监控技术的原理论证

从理论和实验上论证了一种用于掺铒光纤放大器 (EDFA)远程在线监控和判断级连EDFA系统级间断点位置的技术方案。该方案利用频移键控 频分复用 (FSK FDM)技术进行声频副载波调制 ,通过光强度调制实现远程在线EDFA监控信息随主信号的传输。实验测得在副载波调制度为 3 %和 15 %时 ,10Gbit s波分复用 (WDM)光传输系统的功率代价分别为 0 16dB和 0 86dB。采用锁相技术 ,成功进行了 3 %调制度的监控信息解调。说明该方案可以实现对 5级EDFA系统的监控     

Fast wavelength detection technique for multi-wavelength photonic packet networks

A wavelength detection technique for the control of transmitter wavelengths in WDM/FDM optical packet networks is demonstrated. The wavelength of a transmitter can be determined within a single packet duration (1.6 mu s). The authors demonstrate optical frequency detection to an accuracy of +or-75 MHz over a capture range of 6 GHz.<>     

Over-1000-channel ultradense WDM transmission with supercontinuum multicarrier source

In this paper, ultradense wavelength-division multiplexing (WDM) transmission technologies are discussed, and a field demonstration of over-1000-channel ultradense WDM transmission is reported. The generation of an ultradense WDM signal using a supercontinuum multicarrier source that generates more than 1000 carriers and uniform precise channel spacing of 6.25 GHz is presented. The influence of four-wave-mixing generated in the transmission fiber and the requirements placed on the WDM multiplexer and demultiplexer is described. An over-1000-channel ultradense WDM transmission experiment is reported. A 1046 /spl times/ 2.67-Gbit/s 6.25-GHz-spaced ultradense WDM signal is successfully transmitted over 126 km of field-installed fibers in the test bed of JGN II.     

Comparative analysis of the traffic performance of fiber-impairment limited WDM and hybrid OCDM/WDM networks

Optical code-division multiplexing (OCDM) is a technique that is currently generating considerable research interest. This paper analyzes and compares the traffic performance of wavelength-division multiplexing (WDM) and hybrid OCDM/WDM-based optical networks. The analysis considers the influence of the limitations of fiber-induced signal impairments on traffic performance and comparisons are performed for an example network utilizing different standardized fiber types. Furthermore, comparisons of traffic performance are also made between different lightpath schemes used in WDM and OCDM/WDM networks. The analysis results show that the OCDM/WDM lightpath schemes significantly outperform the WDM lightpath schemes for given blocking probability criteria. Moreover, the analysis indicates that fiber nonlinearity (which limits the minimum channel spacing) affects the traffic performance more severely compared to fiber dispersion (limits code cardinality).     

A generalized suboptimum unequally spaced channel allocationtechnique. I. In IM/DD WDM systems

Four-wave mixing (FWM) is the most serious fiber nonlinearity associated with low-input optical power levels in long-haul multichannel optical systems employing dispersion-shifted fiber. To reduce the crosstalk due to FWM, a generalized suboptimum unequally spaced channel allocation (S-USCA) technique is proposed and investigated. Even though the developed technique is useful in combating FWM crosstalk in wavelength division multiplexing (WDM) lightwave systems with up to 12 channels, its main virtue is in designing multichannel WDM lightwave systems with more than 12 channels. Comparisons of power penalty due to FWM between equal channel spacing (ECS) systems and the S-USCA systems are presented. It is shown that for an intensity modulation/direct detection (IM/DD) transmission system operating in an optical bandwidth of 16 nm with 0 dBm (1 mW) peak optical input power per channel, while a conventional ECS WDM system with 0.84-nm channel spacing cannot even achieve a bit-error rate (BER)=10^-9, the suboptimum technique developed in this paper, for the same minimum channel spacing, can achieve a BER=10^-9 with an FWM crosstalk power of less than 1 dB at the worst channel in a 20-channel WDM system     

40Gb／s波分系统设备技术

随着40Gb／s端口路由器的出现,未来几年内40Gb／s波分系统设备将取代现有的10Gb／s波分系统设备,就像前几年10Gb／s波分系统设备取代2．5Gb／s波分系统设备一样。然而,40Gb／s波分系统有很多传输限制因素,包括光放大器自发辐射噪声、光纤非线性效应、色散、偏振模色散等等。为实现40Gb／s的波分传输,采取新型调制码型、可调色散补偿、偏振模色散补偿等措施至关重要。     

Simultaneous all-optical frequency downconversion technique utilizing an SOA-MZI for WDM radio over fiber (RoF) applications

Simultaneous all-optical frequency-downconversion technique utilizing a semiconductor optical amplifier Mach-Zehnder interferometer (SOA-MZI) is experimentally demonstrated, and its application to a wavelength-division-multiplexing (WDM) radio over fiber (RoF) uplink is proposed. The conversion efficiencies from 22.5 (f/sub RF/) to 2.5 GHz (f/sub IF/=f/sub RF/-2f/sub LO/) are in the range from 1.5 to 3 dB for the optical RF wavelength between 1548 and 1558 nm. Error-free simultaneous all-optical frequency downconversion of the two WDM RoF upstream channels that carry 155-Mb/s differential phase-shift keying data at 22.5 GHz to an optical intermediate frequency signal having the frequency of 2.5 GHz with the power penalty less than 0.1 dB at the bit error rate of 10/sup -8/ is achieved.     

Performance Comparison of Duobinary Formats for 40-Gb/s and Mixed 10/40-Gb/s Long-Haul WDM Transmission on SSMF and LEAF Fibers

Duobinary formats are today considered as being one of the most promising cost-effective solutions for the deployment of 40-Gb/s technology on existing 10-Gb/s WDM long-haul transmission infrastructures. Various methods for generating duobinary formats have been developed in the past few years but to our knowledge their respective performances for 40-Gb/s WDM transmission have never been really compared. In this paper, we made an extensive numerical evaluation of the robustness of these different types of duobinary transmitter to accumulation of ASE noise, chromatic dispersion, PMD but also to single-channel and WDM 40-Gb/s transmission impairments on standard single-mode fiber. A numerical evaluation of the ability of duobinary format for mixed 10/40-Gb/s WDM long-haul transmission with 50-GHz channel spacing is also led, on both standard single-mode and LEAF fibers, and compared to DQPSK format. In order to clearly identify the limiting transmission effects on each of these two fiber types, the assessment of the performance of a 50-GHz spaced WDM 40-Gb/s long-haul transmission using either duobinary or DQPSK channels only is implemented at last.      

Eight-channel bidirectional WDM add/drop multiplexer

The authors propose and demonstrate an eight-channel reconfigurable bidirectional wavelength division multiplexed (WDM) add-drop multiplexer in which all channels can be added/dropped independently in either direction. The performance of the bidirectional WDM add/drop multiplexer is experimentally studied for a data rate of 10 Gbit/s per channel, providing an overall capacity of 80 Gbit/s. It is found that the performance of the add/drop multiplexer is not degraded by a backward propagating signal     

Advances in multichannel MultiGbytes/s bit-parallel WDM singlefiber link

For ultra-high-speed single media parallel interconnects, an all optical single fiber WDM format of transmitting parallel bits rather than a fiber ribbon format-where parallel bits are sent through corresponding parallel fibers in a ribbon format, can be the media of choice. Here, we discuss the realization of a multi-km×Gb/s bit-parallel WDM (BP-WDM) single fiber link. The distance-speed product of this single fiber link is more than several orders of magnitude higher than that of a fiber ribbon link. The design of a 12 b parallel channels WDM system operating at 1 Gb/s per channel rate through a single fiber is first presented. Experimental results for a two channel system operating at that rate are given. Further improvement of distance-speed product for the BP-WDM link can be obtained with JPL's newly developed 20 Gb/s per channel laser diode array transmitter. Also, new computer simulation results on how a large amplitude co-propagating pulse may induce pulse compression on all the co-propagating data pulses, thereby improving the shaping of these pulses for a WDM system, are presented and discussed. The existence of WDM solitons is also shown