Chen Zhangyuan

Comparison of node architectures for elastic optical networks with waveband conversion

In Elastic Optical Networks (EONs) with flexible bandwidth allocation, the blocking probability is high because of spectral contention. Similar to the functionality of wavelength conversion in Wavelength-Division-Multiplexing (WDM) networks, waveband conversion has been proposed to solve spectral contention in EONs. In this paper, we discuss the design of node architectures for an EON with waveband conversion. Four node architectures with shared Tuneable Waveband Converters (TWBCs) are proposed, and their blocking performances are evaluated by simulation. Simulation results show that the blocking probability of a node is significantly improved by waveband conversion. The sharing efficiency of waveband converters is also investigated. Simulation results show that at the same blocking rate, the node architecture with converters shared per node can save more than 20% waveband converters compared with that of the one with converters shared per link.

Theory analysis of the handover challenge in Express Train Access Networks (ETAN)

To handle the handover challenge in Express Train Access Networks (ETAN), mobility fading effects in high speed railway environments should be addressed first. Based on the investigation of fading effects in this paper, we obtain two theoretical bounds: HO-Timing upper bound and HO-Margin lower bound, which are helpful guidelines to study the handover challenge today and in the future. Then, we apply them to analyze performance of conventional handover technologies and our proposal in ETAN. This follow-up theory analyses and simulation experiment results demonstrate that the proposed handover solution can minimize handover time up to 4 ms (which is the fastest one so far), and reduce HO-Margin to 0.16 dB at a train speed of 350 km/h.

Ultra-Long Haul L-Band WDM Transmission over a Standard Single-Mode Fibre Loop Using DCF+CFBG Hybrid Dispersion Compensation

We demonstrate a 10.7 Gb/s-line-rate L-band wavelength-division-multiplexer (WDM) loop transmission over a 1890-km standard single-mode fibre (SSMF) with a 100-km amplifier spacing as well as non-return-to-zero (NRZ) format. The dispersion compensating fibre (DCF) plus chirped fibre Bragg grating (CFBG) is employed for hybrid inline dispersion compensation. The power penalty of each channel is less than 3 dB after three-loop transmission. The experimental results show that high-performance CFBGs can be successfully used in ultra-long haul (>1000 km) WDM systems. We also point out that the all-CFBG compensation scheme is not suitable for re-circulating loop transmissions.

43 Gb/s DWDM Optical Transmission System Using NRZ Format and Electro-absorption Modulation

We demonstrate experimentally a 43 Gb/s DWDM optical transmission system over 900 km single mode fiber with 100 km spans using NRZ format and Raman amplification without FEC. A commercial LiNbO3 modulator and a self-designed 43 Gb/s transmitter based on electro-absorption modulator and are compared in the system, and for the first time the electro-absorption modulation is shown to be able to realize up to 1200 km transmission with a power penalty less than 2 dB. This system includes 8 channels of 43 Gb/s DWDM signal and can support 40 channels over C band. Transmission over 1500 km is also presented and the influence of polarization mode dispersion is shown to be a main limitation.

Numerical analysis of four-wave-mixing based multichannel wavelength conversion techniques in fibers

We numerically investigate four-wave-mixing (FWM) based multichannel wavelength conversion for amplitude-modulated signals, phase-modulated signals, together with mixed amplitude and phase modulated signals. This paper also discusses the influence of stimulated Brillouin scattering (SBS) effects on high-efficiency FWM-based wavelength conversion applications. Our simulation results show that DPSK signals are more suitable for FWM-based multichannel wavelength conversion because the OOK signals will suffer from the inevitable datapattern-dependent pump depletion. In future applications, when the modulation format is partially upgraded from OOK to DPSK, the influence of OOK signals on the updated DPSK signals must be considered when using multichannel wavelength conversion. This influence becomes severe with the increase of OOK channel number. It can be concluded that DPSK signals are more appropriate for both transmission and multichannel wavelength conversion,especially in long haul and high bit-rate system.

A Novel Optical Modulation Format CSNRZ

In this letter, together with the transmitter configuration, a novel modulation code format named carrier-suppressed nonreturn-to-zero (CSNRZ) is proposed. Unlike the conventional nonreturn-to-zero code (NRZ), return-to-zero (RZ) and carrier-suppressed return-to-zero (CSRZ) signals, this optical signal has reverse-phase optical amplitude in the periods corresponding to 0 bit compared to 1 bit. With an additional transform module at the receiver side, this reverse-phase optical power can reduce the transmission power penalty due to fiber nonlinearity.

Experimental study of the transient power overshoot in backward-pumped Raman amplified WDM systems

The channel distribution of the transient power overshoots, caused by the channels adding up, in backward pumped Raman amplified wavelength division multiplexed systems is studied experimentally. It is found that the time for the output power of different signal to drop from the maximum values to the minimum values is not equal to each other. The shorter the signal wavelength is, the smaller the time is. And the shape of the channel distribution of the maximal value of the power overshoot in the output signal is similar to that of the system ON-OFF gain distribution.