Chunmin Xia

Nonlinear Electrical Equalization for Different Modulation Formats With Optical Filtering

Based on bit-error-ratio simulations, we investigate electrical-dispersion-compensation performance by using a nonlinear electrical equalizer based on nonlinear Volterra theory for different modulation formats. This nonlinear equalizer is compared to conventional decision-feedback equalizer as well as to maximum-likelihood sequence estimation. Especially, we show that nonlinear equalizers, in conjunction with narrowband optical filtering of the light signal, result in improved performance. First of all, the system can benefit from the noise reduction due to narrowband filtering. Second, interacting with chromatic dispersion, nonlinear equalizers benefit from the improved dispersion tolerance through spectrum reshaping by narrowband optical filtering. Finally, nonlinear equalizers can efficiently mitigate the distortion resulting from strong optical filtering

On the performance of the electrical equalization technique in MMF links for 10-gigabit ethernet

In this paper, the electrical equalization technique utilized in multimode fiber (MMF) links for 10-Gigabit Ethernet is reported. This paper presents and compares three kinds of equalizers: linear equalizer, decision feedback equalizer (DFE), and a nonlinear finite-impulse-response DFE (NL-FIR-DFE) based on the analysis of nonlinear operations of direct modulation and detection in MMF links. Computer simulations reveal that NL-FIR-DFE exhibits superior performance in comparison with normal DFE. The equalization performance for an MMF channel with bandwidth 500 MHz-km as well as 160 MHz-km is demonstrated. It is demonstrated that with direct modulation of cost-effective vertical-cavity surface-emitting laser (VCSEL) or Fabry-Perot laser, the transmission distance for installed MMF with a bandwidth of 500 MHz-km at 10 Gb/s can be extended to 300 m with an appropriate offset restricted mode launch condition by utilizing normal DFE and to more than 650 m for NL-FIR-DFE. Moreover, it is shown that the transmission distance for an MMF with a bandwidth of 160 MHz-km can reach 300 m with more than seven times bandwidth improvement by using NL-FIR-DFE.

Electrical dispersion compensation for different modulation formats with optical filtering

We present electrical dispersion compensation by using maximum-likelihood-sequence-estimation (MLSE) and decision-feedback-equalization for different modulation formats. Especially, MLSE performance with strong optical filtering is investigated.

Experimental investigations of mode group diversity multiplexing on multimode fibre

We present experimentally the possibility of mode multiplexing using two launch positions and successful demultiplexing using two detection areas in order to double the data rate from 10 Gb/s to 20 Gb/s over multimode fibre.

Mitigation of Optical Intrachannel Nonlinearity Using Nonlinear Electrical Equalization

A nonlinear electrical equalization technique is proposed to mitigate the intra-channel nonlinearities in 40Gb/s optical fiber communications. High efficiency of this nonlinear equalizer for mitigation of nonlinearities is demonstrated.

Statistical analysis of electrical equalization of differential mode delay in MMF links for 10-Gigabit Ethernet

Through statistical analysis of a large number of worst-case multimode fiber channels, we demonstrate that using electrical equalization, the 300 m-transmission reach at 10 Gb/s can be guaranteed for installed multimode fiber under any launch condition.

Electronic Channel Equalization Techniques

This paper presents the key design approaches and results in the field of optical impairment distortion compensation by electronic means, as an outcome of the studies and research innovations developed within the COST 291 action. The research topics addressed are related with chromatic dispersion and nonlinearities, with particular reference on FFE/DFE and MLSE-based equalizers as well as with the assistance of different modulation formats. Additionally, the use of electronic compensation in metroaccess applications is examined with reference on studies related with the performance enhancement of DML transmitters.

Improved EDC performance for different duobinary modulation formats with optical filtering

Nonlinear EDC including nonlinear Volterra based equalizer and MLSE are investigated and compared for different duobinary formats with optical filtering at 43 Gb/s data rate.

Electrical Mitigation of Penalties Caused by Group Delay Ripples for Different Modulation Formats

Electrical equalizers are proposed to mitigate the distortions caused by group delay ripples (GDRs) of cascaded optical filters (e.g., fiber Bragg gratings for chromatic dispersion (CD) compensation). Different electrical equalizers including feedforward equalizer (FFE), decision-feedback equalizer (DFE), nonlinear FFE-DFE, and maximum-likelihood sequence estimator are investigated and compared comprehensively for four different modulation formats: ON-OFF keying, optical duobinary, optical single sideband, and differential phase-shift keying. Especially, we find that the relationship of electrical equalization performance on the modulation format is very similar for the mitigation of GDR and CD.

Combination of optical and electrical compensation of differential mode delay in MMF links for 10-gigabit ethernet

We present both optical and electrical compensation of Differential Mode Delay (DMD) in Multimode Fiber (MMF) links. Based on the rigorous analysis of optical compensation of DMD, a new kind of Dispersion Compensating Fiber (DCF) is proposed. We show that 10Gb/s Ethernet reach for conventional MMF can be extended to 300m by splicing 10~35m of this DCF. We prove that ISI resulting from DMD can be mitigated with electrical compensation by using linear or nonlinear equalizers. Moreover, we demonstrate that combination of optical and electrical compensation can dramatically enhance the bandwidth of installed MMF. Simulations carried out on six types of typical installed MMF for Overfilled Launch (OFL) as well as Restricted Mode Launch (RML) condition exhibit that transmission distance for conventional MMF with bandwidth-distance product 500MHz-km can be extended to 1000m or beyond with 2dB Eye-Opening Penalty (EOP).