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All optical – multi-wavelength regenerators QD-SOA and Fibre based approaches. C. Kouloumentas, M. Spyropoulou, Ioannis Tomkos High Speed Networks and Optical Communications Group Markopoulou Ave., PO. BOX 68, 190 02 Peania, Athens, Greece. ePhoton/ONe meeting, Barcelona, February 2007.
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All optical – multi-wavelength regenerators QD-SOA and Fibre based approaches C. Kouloumentas, M. Spyropoulou, Ioannis Tomkos High Speed Networks and Optical Communications Group Markopoulou Ave., PO. BOX 68, 190 02 Peania, Athens, Greece ePhoton/ONe meeting, Barcelona, February 2007
Multi-wavelength 2R operation at 40 Gbps and 160 Gbps based on two different techniques (QD-SOA and HNLF based) Subsystem Specifications Cascadability studies in a network scenario Outline
All-optical regeneration based on Quantum Dot Semiconductor Optical Amplifiers M. Spyropoulou, S. Sygletos and Ioannis Tomkos ePhoton/ONe meeting, Barcelona, February 2007
XGM between λi and λ’I, where i is the number of input channels The input signal polarity is maintained with the use of two QDSOAs in series Subsystem Configuration Fig. 1: a) Subsystem description. b) Neighbouring channels within the inhogeneously broadened gain spectrum of the QD-SOA.
Q-factor improvement: 2.7 dB for ch1 3 dB for ch2 Two-channel operation at 40 Gbps • Symmetrical behavior of the two channels • Channel spacing = 20nm with respect to the center of inhomogenous broadening • Detuning = 200 GHz Fig. 4:Eye diagrams for channel 1 and channel 2 at the a) input to the subsystem and b) output of the subsystem at 40Gbps.
Channel spacing = 20nm, detuning frequency = 600GHz Amplitude variation suppression at the marks Q-factor improvement 1.7 dB and 2 dB for ch1 and ch2, respectively. Two-channel operation at 160 Gbps Fig. 5:Eye diagrams for channel 1 and channel 2 at the a) input to the subsystem and b) output of the subsystem at 160Gbps.
Extinction ratio improvement along the cascade for Psat≥ 10dBm Q-factor improvement is subsequent due to the drop of the power level of the spaces. Eyediagrams illustrate that suppression of the amplitude jitter at the power level of the marks also contributes to the improvement of the Q-factor and it indicates the regenerative action of the QDSOAs. Cascadability with the use of SAs (1) Fig. 8: Cascade of QDSOA based regenerative subsystems with use of the saturable absorber (SA). Fig. 9: Extinction ratio of the output signal as a function of the number of cascaded nodes for different values of Psat at 40 Gbps.
At the output of Node 6, there is 5dB extinction ratio improvement and 4.2dB Q-factor improvement for single-channel operation at 40 Gbps. Time shift of the peak power level for 1 ps has introduced duty cycle distortion at the output of Node 6. Cascadability with the use of SAs (2) Ring network with 6 nodes Fig. 10: Eye diagrams at the output of the first, third and sixth node for saturation power 10 dBm at 40 Gbps.
All-optical regeneration for two input channels at 20 nm channel spacing has been achieved for both 40 Gbps and 160 Gbps operation Extinction ratio degradation has been compensated with the use of a saturable absorber Effective cascadability has been shown for up to 6 Nodes for single channel operation at 40 Gbps Conclusions
Fiber - based multi-wavelength 2R regeneration Christos Kouloumentas and Ioannis Tomkos ePhoton/ONe meeting, Barcelona, February 2007
Extension of the concept for multi - channel regeneration Use of multiple cells Each one consisting of an HNLF-PD (positive dispersion) and a DCF (negative dispersion) High local dispersion and low average dispersion enables SPM and minimizes XPM
Optimization of the multi-channel regenerator 4 x 40 Gb/s WDM channels Assessment of the regeneration performance is based on the comparison of the Q-factor between the regenerated and the unregenerated channels
Improvement of the Q-factor The parameter is the extinction ratio of the modulators Since the proposed regenerator acts as power limiter, it performs much better when the ER of the modulators is high and noise in “0s” is not favored 24 dB input OSNR
Electrical eye diagrams of one of the middle channels 24 dB input OSNR 15 dB ER of the modulators 2 cells Unregenerated channel 4 cells 6 cells 8 cells 10 cells
All-optical regeneration for four input channels at 600GHz channel spacing has been achieved at 40Gbps Up to 7 channels can be supported with good cascadeability performance of up to 6 nodes (2R only) Regeneration at 160 Gbps operation has been also demonstrated Conclusions