Nonlinearity mitigation in phase-sensitively amplified optical transmission links

The fundamental limitations in fiber-optic communication are caused by optical amplifier noise and the nonlinear response of the optical fibers. The quantum-limited noise figure of erbium-doped fiber amplifier (EDFA) or any phase-insensitive amplifier is 3 dB. However, the noise added bythe amplification can be reduced using phase-sensitive amplifier (PSA) whose quantum-limited noise figure is 0 dB. PSAs can also compensatefor the nonlinear distortions from the optical fiber with copier-PSA implementation. At the transmitter, a copier which is nothing but aphase-insensitive amplifier is used to create a conjugated copy of the signal. The signal and idler are co-propagated in the span, experiencingcorrelated nonlinear distortions. The nonlinear distortions are reduced by the all-optical coherent superposition of the signal and idler in thePSA.In this work, an analytical investigation is performed for the nonlinearity mitigation using the PSAs, by calculating the residual nonlineardistortion after the coherent superposition in PSAs. The optical bandwidth and the dispersion map dependence on the nonlinearity mitigationin the PSAs are analytically and experimentally studied. A modified Volterra nonlinear equalizer (VNLE) is used to reduce the residual nonlineardistortions after PSAs. Experiments were performed to show that PSAs can mitigate cross-phase modulation (XPM), which was evidentby observing the constellation diagrams. The maximum allowed launch power increase was also measured to quantify the XPM mitigation. Tothe best of our knowledge, this is the first experiment that showed the mitigation of XPM in a phase-sensitively amplified transmission link.Also, the effectiveness in mitigating self-phase modulation (SPM) and XPM using a PSA is studied

Optical frequency comb source for next generation access networks

The exponential growth of converged telecommunication services and the increasing demands for video rich multimedia applications have triggered the vast development of optical access technology to resolve the capacity bottleneck at metropolitan-access aggregations. To further enhance overall performance, next generation optical access networks will require highly efficient wavelength division multiplexing (WDM) technology beyond the capability of current standard time division multiplexed (TDM) systems. The successful implementation of future-proof WDM access networks depends on advancements in high performance transmission schemes as well as economical and practical electronic/photonic devices. This thesis focuses on an investigation of the use of optical frequency comb sources, and spectrally efficient modulation formats, in high capacity WDM based optical access networks. A novel injected gain switched comb generation technique which deliver simplicity, reliability, and cost effectiveness has been proposed and verified through experimental work. In addition, a detailed characterization of the optical comb source has been undertaken with special attention on the phase noise property of the comb lines. The potential of the injected gain switched comb source is then demonstrated in a digital coherent receiver based long reach WDM access scenario, which intends to facilitate 10 - 40 Gbit/s data delivery per channel . Furthermore, an optical scalar transmission scheme enabling the direct detection of higher order modulation format signals has been proposed and experimentally investigated

Advanced Digital Signal Processing Techniques for High-Speed Optical Links

L'abstract è presente nell'allegato / the abstract is in the attachmen

Semiconductor Laser Dynamics

This is a collection of 18 papers, two of which are reviews and seven are invited feature papers, that together form the Photonics Special Issue “Semiconductor Laser Dynamics: Fundamentals and Applications”, published in 2020. This collection is edited by Daan Lenstra, an internationally recognized specialist in the field for 40 years