A novel 10-GHz picosecond pulse source consisting of an electroabsorption modulator (EAM) and a subsequent well-designed pulse compressor is demonstrated experimentally. Among its advantages are stable operation and a tunable repetition rate. A 1.1-ps transform-limited ultrashort pulse with no pedestal is obtained. As an illustration of its use, the obtained high-quality pulse is applied to measure other EAMs' optically or electrically induced temporal transmission windows.
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.
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.