Short Courses

SC105 Modulation Formats and Receiver Concepts for Optical Transmission Systems

Sunday, February 24, 9:00 a.m. - 12:00 p.m.
Peter J. Winzer, Sethumadhavan Chandrasekhar; Bell Labs, Alcatel-Lucent, USA

Level: Advanced Beginner (basic understanding of topic is necessary to follow course material)

Course Description
Progress in high-speed electronics and opto-electronics have led to single-channel data rates of 40 Gbit/s and above over the last few years. Concurrently, advances in optical filter design and optical multiplexer/demultiplexer technologies have brought down optical filter bandwidths to several tens of GHz. Together, these two trends have enabled ultra-dense channel spacings in wavelength division multiplexing (WDM) systems, and have made spectral efficiency a key issue in optical communications research. On the other hand, the impact of various impairments accumulated along a fiber-optic transmission line becomes more detrimental at higher bit rates and closer channel spacings, requiring the need for robust modulation formats and receiving techniques. The main focus of research and development has thus shifted to a quest for tolerant format-receiver combinations.

This course gives an overview of modulation formats for optical networking applications and outlines state-of-the-art methods to generate these formats. The course also addresses important issues of optical receiver design and optimization, presents widely used receiver performance measures, and discusses important receiver performance degradations and design tradeoffs, with an outlook to advanced optical receiver designs utilizing adaptive electronic post-processing and equalization. Finally, it highlights the interdependence of modulation format, receiver parameters and transmission impairments accumulated along the fiber path (e.g., optical noise, intra-channel and inter-channel crosstalk, optical filter cascades, residual chromatic dispersion, and polarization mode dispersion, among others).

Benefits and Learning Objectives
This course should enable you to:

• Discuss the main goals and important signal impairments in optical networking scenarios.
• Get an overview of promising optical modulation formats envisaged for next-generation fiber optic communications.
• Generate advanced optical modulation formats using state-of-the-art opto-electronic components.
• Explain the spectral and temporal properties of spectrally efficient formats.
• Work with optical receiver performance attributes, such as “sensitivity” and “required OSNR.”
• Discuss the trade-offs involved in optimizing high performance optical receivers.
• Recognize the interplay between modulation format, receiver design, and transmission impairments.
• Get an insight into future trends regarding advanced modulation techniques and receiver concepts.

Intended Audience
This is an advanced-level course intended for a diverse audience including lightwave system engineers, opto-electronic subsystem designers, and optical filter technologists. Some basic knowledge of current optical modulation and detection technologies and techniques will help in better understanding the course. The concepts described in the course will be beneficial to the scientific community engineering next-generation optical transmission systems.

Instructor Biographies
Peter J. Winzer received his Ph.D. in electrical engineering/communications engineering from the Vienna University of Technology, Vienna, Austria, in 1998. His academic work, largely supported by the European Space Agency (ESA), was related to the analysis and modeling of space-borne Doppler wind lidar and highly sensitive free-space optical communication systems. In this context, he specialized on optical modulation formats and high-sensitivity receivers using coherent and direct detection. He continued to pursue this field of research after joining Bell Labs in November 2000, where he focused on Raman amplification, optical modulation formats, advanced receiver concepts, and digital signal processing techniques for 10, 40, and 100-Gb/s fiber-optic communication systems.

Sethumadhavan Chandrasekhar received the Ph.D. in physics from the University of Bombay, Bombay, India, in 1985. He joined Lucent Technologies, Bell Laboratories (formerly AT&T Bell Laboratories), Holmdel, New Jersey, in 1986. He has worked on III-V compound semiconductor devices such as photodetectors, heterojunction phototransistors, bipolar transitors (HBTs) and high-speed optoelectronic integrated circuits (OEICs), advanced receive-side digital signal processing, novel modulation formats and high speed DWDM optical networking systems. His current activities include ROADMs, mesh optical networking and hybrid DWDM 10G/40G/100G transmission. He is a fellow of the IEEE.