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All-optical Sampling And Signal Regeneration Techniques In Optical Fiber Communication

Posted on:2011-05-30Degree:MasterType:Thesis
Country:ChinaCandidate:P X DuanFull Text:PDF
GTID:2208360308967351Subject:Optical Engineering
Abstract/Summary:PDF Full Text Request
Fiber communication systems have been rapidly developed, the bit rate of the single channel was 44.7Mb/s in 1970s, increasing to 40Gb/s nowadays. However, in the nodes of optical networks, the transmission signal is processed in the electronic domain, facing many difficulties such as optical-to-electrical-to-optical (OEO) bottleneck, large power consumption and the capacity mismatch between the fiber transmission system and electronic signal processing. All-optical processing, i.e. signal processing performed in the optical domain, attracts considerable research attention, because it can provide ultra-fast operation speed, small power consumption, and also can remove OEO bottleneck. In this thesis, we propose and demonstrate a novel scheme to realize all-optical sampling and all-optical 2R (re-amplifying and reshaping) regeneration, which are very important function blocks in the field of optical signal processing area.In the all-optical processing technologies, the utilization of the nonlinear effects of semiconductor optical amplifiers (SOAs) is a mainstream research topic, since the SOA-based approaches offer some essential advantages, for example, large nonlinear efficiency, small footprint, and capability for large-scale optical integration. In general, the SOA has several nonlinear effects such as cross gain modulation (XGM), cross phase modulation (XPM), four wave mixing (FWM), nonlinear polarization rotation (NPR), et al. In this thesis, we use the NPR effect to realize all-optical sampling and all-optical 2R generation.All-optical sampling is a fundamental part in the structure of the analog-to-digital conversion (ADC) processing, which is necessary for digital signal processing. In the optical sampling, ultra-short optical pulses are used to sample analog optical signal. Compare to electronic sampling pulses, the width of optical pulses can be much narrower, and the jitter of it can be much smaller, thus optical sampling can achieve much better results. We use the NPR effect in SOA to realize all-optical sampling. 40GHz optical pulses sampled 2.5GHz analog signal is demonstrated both in simulation and experiment.All-optical regeneration is important to maintain the signal quality in the optical networks, because the transmission optical signal will be degraded after a long distance transmission, due to losses, dispersion and noise in the fiber. The regeneration is used to restore the degraded signal, usually including re-amplifying, re-shaping and re-timing three function blocks, i.e. 3R regeneration. It is so-called 2R regeneration if only the first two function blocks are involved. 2R regeneration is crucial especially in the metropolitan area network and local area network, where the distortion in the time domain is negligible. In our approach, 2R regeneration is achieved on the NPR effect in SOA. Simulation and experiment results demostrate that our 2R regeneration scheme works successfully. We achieve an extinction ratio improvement of 8.3dB at a bit-rate of 10Gbit/s. In the bit-error-rate measurements, the power penalty is improved by 6dB.
Keywords/Search Tags:all-optical processing, all-optical sampling, all-optical 2R regeneration, semiconductor optical amplifier, nonlinear polarization rotation
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