Advanced Optical Modulation Formats

INVITED P A P E R Adva n ced Op t ic a lM od ulation Formats Choice of the right modulation format is key to building flexible and cost-effective high-capacity optically routed wavelength division multiplexed fiber networks. B y Peter J. Winzer, Senior Member IEEE, and Rene ´-Jean Essiambre, Member IEEE ABSTRACT | Fiber- optic communicati on systems form the high-capacit y trans port infr astructure that enables global broadband data services and advanced Internet applications. The desire for higher per-fiber transport capacities and, at the same time, the drive for lower costs per end-to-end transmitted infor mation bit has led to optically routed networks with high spectral efficiencies. Among other enabling technologi es, advanced optical modul ation formats have become key to the design of modern wavelength division multiplexed (WDM) fiber systems. In this paper, we review optical modulation formats in the broader context of optically routed WDM networks. We discuss the generation and detection of multigigabit/s intensity- and phase-modulated formats, and highlight their resil- ience to key impairments found in optical networking, such as optical ampl ifier noise, mult ipat h inter ference, chromatic dispersion, polarizati on-mode dispersion, WDM crosstalk, concatenated optical filtering, and fiber nonlinearity. KEYWORDS | Differential phase modulation; digital modulation; intensity modulation; optical communication; optical networks; wavelength division multiplexing (WDM) LIST OF ACRONYMS ACRZ Alt ern ate -ch irp ret urn -to -zero AMI Al ternate- ma rk inversion ASE Ampl if ied sp on ta ne ou s emission BER Bit-error ratio CD Chromatic dispersio n C-NRZ Chi rpe d non ret urn -to -zero CRZ Chirped return-to- ze ro CSRZ Car rie r-supp res sed ret urn -to -ze ro DB Duobinary DCF Di spersi on-c ompensating fi be r DCS Duobinar y ca rr ier su ppressed DFB Di st ribu te d fe ed ba ck laser DGD Di ff er enti al gr ou p de la y DI Delay interferometer DM Data modulation DMF Data mo du la ti on fo rmat DML Di re ct ly mo du la te d la ser DPSK Di ff er ential phas e shift keyi ng DQP SK Dif fer ent ial qua dra tur e phase shi ft k eyi ng DST Di sper si on-s upport ed tr ansmission EAM Electroab so rpti on modulator EML Electroabsorption modulated laser EPD Electr onic pr edis to rtion F EC F orwa rd e rr or co rre cti o n FM Frequency modula tion FWM F ou r- wave mi xi ng GVD Gr oup ve lo ci ty di sp ersion IFWM Intr ac ha nnel fo ur-wav e mi xin g ISD Info rmatio n spec tr al de nsit y I SI In ter sy mb ol in t er fe r en ce ITU Internationa l teleco mmunicat io n union IXPM Int rac han nel cross- pha se mod ula tio n M-ASK Mul til evel amp litude shi ft key ing MI Modula tion instabilit y MLSE Max imum-li kel iho od seq uence est ima tor MP I M ul t ip ath i nte rf ere nc e MZM Mach–Zeh nd er modulator NL Nonlinearity NRD Net re si dual disp er sion N RZ N on re t ur n- to -ze ro NZDF Nonz er o di spersi on shif ted fi ber OA Optical amplifier OADM Optical add /dr op mult iple xer OOK On/off keying OSNR Opti ca l si gnal -to-noise ratio OXC Opti ca l crossconnect PASS Phas ed ampl itude shif t signaling Manuscript received June 13, 2005; revised November 28, 2005. The authors are with Bell Labs, Lucent Technologies, Holmdel, NJ 07733 USA (e-mail: [email protected]). Digital Object Identifier: 10.1109/JPROC.2006.873438 952 Proceedings of the IEEE | Vol. 94, No. 5, May 2006 0018-9219/$20.00 Ó2006 IEEE Authorized licensed use limited to: Chalmers University of Technology. Downloaded on August 04,2010 at 12:51:26 UTC from IEEE Xplore. Restrictions apply.

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