The latest hot topics of high-spectral density optical communication systems using digital coherent optical fibre communication technologies are covered by this book. History and meaning of a "renaissance" of the technology, requirements to the Peta-bit/s class "new generation network" are also covered in the first part of this book. The main topics treated are electronic and optical devices, digital signal processing including forward error correction, modulation formats as well as transmission and application systems. The book serves as a reference to researchers and engineers.

Overview and System Technologies.- Social Demand of New Generation Information Network: Introduction to High Spectral Density Optical Communication Technology.- Coherent Optical Communications: Historical Perspectives and Future Directions.- Ultrahigh Spectral Density Coherent Optical Transmission Technologies.- "Quasi Ultimate" Technique.- High-Speed and High-Capacity Optical Transmission Systems.- Advanced Modulation Formats.- Multilevel Signaling with Direct Detection.- High Spectral Efficiency Coherent Optical OFDM.- Polarization-Division-Multiplexed Coherent Optical OFDM Transmission Enabled by MIMO Processing.- No-Guard-Interval Coherent Optical OFDM with Frequency Domain Equalization.- QPSK-Based Transmission System: Trade-Offs Between Linear and Nonlinear Impairments.- Real-Time Digital Coherent QPSK Transmission Technologies.- Challenge for Full Control of Polarization in Optical Communication Systems.- Opto-Electronics Devices.- Semiconductor Lasers for High-Density Optical Communication Systems.- Monolithic InP Photonic Integrated Circuits for Transmitting or Receiving Information with Augmented Fidelity or Spectral Efficiency.- Integrated Mach-Zehnder Interferometer-Based Modulators for Advanced Modulation Formats.- Key Devices for High-Speed Optical Communication and Their Application to Transceiver Module.- Forward Error Correction.