Yanfu Yang

A study on the wavelength conversion and all-optical 3R regeneration using cross-absorption modulation in a bulk electroabsorption modulator

A 40-Gb/s 3R regenerator with a two-ring injection mode-locked fiber laser as the clock recovery and an electroabsorption modulator (EAM) as the reshaping optical decision gate is proposed and demonstrated. The cross-absorption modulation effect in a bulk EAM was also numerically modeled. Using this model, both the shape and the extinction ratio of the optical decision gate are optimized. The model is also employed to investigate the tolerance of the timing jitter, the chromatic dispersion, and the polarization mode dispersion of an all-optical 3R regenerator based on a bulk EAM decision gate. The operation margin of the 3R regenerator is presented. The theoretical results agree well with the experimental results

Simple pulse compression scheme based on filtering self-phase modulation-broadened spectrum and its application in an optical time-division multiplexing system

We propose a simple and stable pulse compression scheme based on a filtering self-phase modulation broadened spectrum in a highly nonlinear fiber. It is found experimentally that under offset filtering the compressed pulse has a better quality compared with center filtering, such as a no pulse pedestal. Furthermore, numerical simulations reveal that the scheme has the potential to improve the pulse extinction ratio during compression. Finally, based on the obtained pulse train the 4 x 10 Gbits/s optical time-division multiplexing system is studied for verification of the high pulse quality. The compression scheme has the advantages of simple configuration, being pedestal-free, and having a high pulse extinction ratio.

First- and second-order PMD mitigation using 3R regeneration

We experimentally studied the PMD mitigation schemes using two different optical 3R regenerators. One is based on synchronous modulation and the other using an optical decision gate based on an electroabsorption modulator. The experimental results show that both schemes are useful to mitigate the signal quality degeneration induced by both first and second order PMD. System performance without and with 3R regeneration was separately studied by eye analysis and BER measurements. The signal quality was significantly improved by 3R regeneration under serious 1st-order PMD (up to 40% of the bit interval) combined with 2nd-order PMD (up to ~520ps2). We compared the performance between the two different 3R regenerators. The results show that 3R regenerator using an optical decision gate has a superior performance in synchronously mitigating 1st-order and 2nd-order PMD. Moreover, 3R based on EAM performs wavelength conversion simultaneously, which can be used to avoid wavelength blocking at nodes of the optical networks. Further studies indicate that 3R regenerators have the potential to combat with the effects of PMD combined with PDL and PHB. The limitation of the two schemes is also discussed.

A simple method of generating time division multiplexed pulse trains with correlated and controllable phase

We demonstrate a simple method of generating time division multiplexed pulse trains with correlated and controlled phase, only using low-cost birefringent crystals and polarizers. As an illustration of this method, we achieve carriersuppressed RZ (CS-RZ) pulse trains at 20GHz and 40GHz respectively by multiplexing 10GHz ultrashort pulse train. Furthermore, by numerical simulations, it is verified that the suitable phase-modulated pulse train generated by our method can be applied to high speed optical transmission system for suppressing intrachannel nonlinear effects.