Optics Express Focus Issue Features Breakthroughs in Coherent Communication

WASHINGTON, Jan. 17 - Research and subsequent technological advances in coherent optical communication are undergoing a revival, providing new technology platforms for long-distance spectrally-efficient optical transport. An increased number of recent breakthroughs, including real-time measurements of a 40 Gb/s coherent system, digital implementation of fiber impairment compensation, and demonstrations of advanced modulation formats, led the editors of Optics Express to devote the Jan. 21 issue to this field. These breakthroughs at the physical layer will bring about increased speed and connectivity for Internet users in the near future. According to the issue’s editor, Professor Guifang Li of CREOL at the University of Central Florida, “It’s an exciting time for the field of optical communications and coherent optical communication is a very vibrant and rapidly progressing field.” SummaryThis Optics Express focus issue features research by veterans who worked in coherent communication in the 1980s, as well as researchers who entered the field recently. The slowing of coherent optical communication in the 1990s can be attributed to the impracticality of phase and polarization management, implemented in the optical domain using optical phase-locked loops and optical polarization controllers in the 1980s, which are required in a coherent receiver. However, advances in integrated circuits and digital signal processing (DSP) technologies have brought coherent optical communication to the forefront again. These recent advances mirror advances in RF/wireless communications, but DSP-enabled coherent optical communication is advancing at a more rapid pace and offers new possibilities such as fiber nonlinearity compensation.

Key Findings & Selected Papers

The following papers are some of the highlights of the Optics Express focus issue on coherent communication. All are included in volume 16, issue 2, and can be accessed online at www.OpticsExpress.org .

A team from Nortel Networks in Ottawa, Canada demonstrates continuous real-time measurements from a coherent 40 Gb/s transmission system that uses Dual-Polarization Quadrature Phase Shift Keying (DP-QPSK) modulation. “Real-time measurements of a 40 Gb/s coherent system .” Han Sun, Kuang-Tsan Wu, and Kim Roberts, Nortel Networks. pp. 873-879.

Research from the University of Central Florida outlines a universal post-compensation scheme for fiber impairments in wavelength-division multiplexing (WDM) systems based on coherent detection and digital signal processing.“Electronic post-compensation of WDM transmission impairments using coherent detection and digital signal processing .” Xiaoxu Li, Xin Chen, Gilad Goldfarb, Eduardo Mateo, Inwoong Kim, Fatih Yaman, Guifang Li, CREOL, The College of Optics & Photonics, University of Central Florida. pp. 880-888.

Researchers from Japan’s Tohoku University describe 1 Gsymbol/s, 64 and 128 coherent quadrature amplitude modulation (QAM) transmissions over 150 km, in which they employ a frequency-stabilized C2H2 fiber laser, an optical phase-looked loop (OPLL), and a heterodyne detection circuit.“64 and 128 coherent QAM optical transmission over 150 km using frequency-stabilized laser and heterodyne PLL detection .” Masato Yoshida, Hiroki Goto, Keisuke Kasai, and Masataka Nakazawa, Research Institute of Electrical Communication, Tohoku University. pp. 829-840.

About Optics Express

Optics Express, the leading optics journal, reports on new developments in all fields of optical science and technology every two weeks. The journal provides rapid publication of original, peer-reviewed papers. It is published by the Optical Society of America and edited by Martijn de Sterke of the University of Sydney. Optics Express is an open-access journal and is available at no cost to readers online at www.OpticsExpress.org .

EDITOR’S NOTE: For details on any of these papers or to schedule interviews with the lead authors, please contact OSA’s Angela Stark, 202.416.1443, astark@osa.org.