Chi, Nan

Holm-Nielsen, Pablo Villanueva

Jeppesen, Palle

Peucheret, Christophe

Zhang, Jianfeng

The feasibility of an optical FSK labeling scheme is demonstrated. An optical signal consisting of a 10 Gb/s payload and a 312 Mb/s label was generated, and its performance was evaluated in an 88 km transmission link

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Downloaded from orbit.dtu.dk on: Dec 17, 2017A novel optical labeling scheme using a FSK modulated DFB laser integrated with anEA modulatorZhang, Jianfeng; Chi, Nan; Holm-Nielsen, Pablo Villanueva; Peucheret, Christophe; Jeppesen, PallePublished in:Technical Digest Optical Fiber Communication Conference 2003Publication date:2003Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Zhang, J., Chi, N., Holm-Nielsen, P. V., Peucheret, C., & Jeppesen, P. (2003). A novel optical labeling schemeusing a FSK modulated DFB laser integrated with an EA modulator. In Technical Digest Optical FiberCommunication Conference 2003 (Vol. 1, pp. 279-280). IEEE.length converter: IEE Electron. Len. 36, pp. 345- 347 (2000). [3] H. J. Lee, S. J. B. Yoo, V K. Tsui and S. K. Fong, "A simple all-optical label detection and swapping technique incorporating a fiber Bragg grating filter,'. IEEE Photon. Tech. Lett. 13, pp. 635-637 (2001). 141 H. J. Lee, V. Hernandez, V K. Tsui and S. J. B. Yoo, "Simple, polarization-independent, and dis- penion-insensitive SCM signal extraction tech- nique for optical switching systems applications," IEE Electron. Lett. 37, pp. 1240-1241 (2001). This work was partially funded by the Defense Advanced Research Projects Agency (DARPA) and Air Force Research Laboratory under agree- ment number F30602-00-2-0543, by the National Science Foundation under grant number ANI- 998665, and by the support of OlDA and Fitel Technologies. n o s  5 4 5  PM ANovel Optical Labeling Scheme Using a FSK Modulated DFB Laser Integrated with an EA Modulator J. Zhang, N. Chi, P. Holm-Nielsen, C. Peucheret, P. Jepperen, Research Center COM, Technical University of Denmark, Kgs. LynEbx Denmark, Email: jiQcom.dru.dk. The feasibility of an optical FSK labeling scheme is demonstrated. An optical signal consisting of a IOGbis payload and a 312Mbis label was gener- ated, and its performance was evaluated in an 88km transmission link. 1. Introduction All optical label switching implements the packst routing and forwarding functions of multiprotocol label switching (MPLS) directly in the optical layer, which is a promising technology for next generation wavelength division multiplexing (WDM) networks. Several optical labeling meth- ods have been proposed and demonstrated as pos- sible solutions [I], in which the label is attached by time multiplexing or subcarrier multiplexing with the data payload. The optical label can also be achieved by angle modulation that is arthogo- nal to the intensity-modulated payload [2]. In direct detection system, the label information can be modulated using either the differential-phase- shift-keying (DPSK) or frequency-shift-keying (FSK) format. The feasibility ofthe optical DPSK labeling has been experimentally validated [3]. However, this scheme imposes stringent require- ments on the laser linewidth. The scheme of com- bined FSWASK modulation was demonstrated to be more applicable in practical networks [4]. In this paper, we report the construction of a novel optical FSK transmitter and investigation of the optical FSK labeled signal's performance. The generated signal consists of a IOGbis intensity modulated payload and a 312Mbis FSK format label, whose performance was evaluated in a 88km standard single-mode-fiber (SMF) trans- mission link. 2. Operation Principle of the Optical FSK Transmitter The optical FSK transmitter plays m important role in optical labeling. The label information is impressed upon the frequency of the optical carrier through FSK modulation, while keeping its ampli- tude unaffected. Thu the optically labeled packet can be achieved when the payload information is modulated on the amplitude of the carrier. An optical FSK signal can be generated simply by directly modulating the electrical current of a DFB or DBR laser diodes [5]. However, the drive e m n t  variation also results in a simultaneous intensity modulation of the emitted light. As for the optical labeling, such residual intensity modu- lation has a detrimental effect on the ontical packet when the payload information is addid, To overcome this problem, we propose a novel opti- cal FSK label generation scheme based on a com- mercially available integrated DFB lased TUESDAY AFTERNOON I OFC 2003 I VOL. 1 I 279  electroabsorption (EA) modulator, whose config- uration is shown in Fig. 1, m label information Electrical delay line . . . . . . . . . . . . . . . . . . . . . . . . .  . . . . . . . . . . . . . . . . . . . . . . . . .  ........................... Fig. 1. Configuration of the optical FSK transminer I"DYICYn.n 0, D/B ,.I./ ,MI Fig. 2. (a) Characteristics of a DFB laser In such B configuration, the DFB laser is driven with a bias current far above the threshold and a relatively small modulation current is added. The intensity variation of the laser output is then com- pensated through the integrated EA modulator driven with the inverse data In this way, only the frequency modulation is enoected in the final out- panicd by a jdB &tensity wriation. The inte- bated EA modulator Hhows a modulation efficiency ofnearly SdBN, as s h o m  in Fig. 2(b). Both the DFB laser and the EA modulator have 3dB~ modula&n bandwidth of 2.5GHz. Fig. 3 shows the measured eye-diagrams and optical spechum of the FSK modulated signal when the DFB laser was driven with B 90mA bias current and a 30mA modulation current. Without inten- sity compensation, nearly 3dB intensity fluctua- tion was observed, as shown in Fig. 3(a). Both the bias and modulation voltage of the EA modulator quedcy deviation ofIOGHz was 'finally gknerated, as indicated by the spectrum of Fig. 3(c). Fig. 2. (b) Characteristics of EA modulator t i ~ i i ~ i i i t l  Fig 3 (a) Direct output eye-diagram of the DFB Laser I 3  =. Fig. 3 (b) Output eye-diagram after EA compen- sation I m a m  REIi8." m8"IBII IUI 1 WLi Sl  ... ... .I, .. ..... .," I ' . ... ... m.1- ,wA" n.t-0 I_.- Fig. 3 (c) Output spechum after EA compensation 3. Performance of the Optical FSK Labeled Signal To investigate the performance ofthe optical FSK labeling scheme, an 88km SMF transmission link was set up, as shown in Fig. 4. The optically labeled signal consisting of a 10GbIs payload and a 312MbIs label was first generated, then trans- mined over 88km SMF, and finally detected using direct detection receivers. Fig. 4. Experimental Setup Two pseudo-random pattern generators were used to generate the payload and label information. The label information was impressed upon the optical carrier (1555.0 nm) through FSK modula- tion, while the payload information was added by using a IOGbIs Mach-Zehnder intensity madula- tor (MZM). The power of the labeled signal was amplified to IOdBm and input into the fiber. The transmission span consisted of 88km SMF and a matching length of dispersion compensating fiber (DCF). The DCF was inserted into the link based on a hybrid dispersion compensation map (i.e. split before and after the transmission fiber) to piw optimized transmission performance. At the receiver node, the labeled signal was split using a 3dB optical coupler. One arm was directly detected by a photodiode and thus the optical pay- load was converted into the electrical domain. In the other arm, a fiber-Bragg-grating (FBG) was used to filter only a single lobe afthe FSK labeled Authorized licensed use limited to: Danmarks Tekniske Informationscenter. Downloaded on March 03,2010 at 10:34:51 EST from IEEE Xplore.  Restrictions apply. 280 /VOL. 1 / OFC 2003 I TUESDAY AFTERNOON signal, thus achieving the FSK demodulation. The demodulated label was received by an electrical receiver with 1.8 GHz bandwidth. Fig. 5 shows the eye-diagrams of the payload and label. Fig. 5 (c) Eye-diagram of received label (electrical) In the labeling scheme used, interference is inm- duced between the payload and label through the intermodulation distortion, as indicated in Fig. 5(c). The intensity modulation depth of the pay- load is a determining factor. Fig. 6(a) shows the mance can be achieved with ne& 6dB 'extinc- tion ratio. Fig. 6(b) shows the transmission performance of the signal with 6dB extinction ratio. The transmission nenalties for label and payload are 2.2dB and l . idB respectively. 4 5 6 7 8 9  Enincban Rabo O f  Payload LgnalIdB) Fig. 6 (a)~Paylyload and label receiver sensitivity versus extinction ratio af the payload e naa.arnm"*rmn . mmLI.d b.rk,0dar, . bldlnl.,Od.L* a l T  - 7 s  - 9 s  B I  I) . . . .. .. .. . .. . ... . .. . . . . . . ~  .. .. .. . . . D I  .28 a 7  I S  .a a4 I 3  a 2  a, R s r s w e l  Power (d" Fig. 6 (b) BER performance of the optically labeled Signal 4. Conclusions We have proposed a novel optical FSK label gen- eration scheme based on a commercially available integrated DFB laser/ EA modulator. AD optically labeled signal consisting of a l0Gbls payload and a 3 l2Mbln label was generated. Both payload and label data could be recovered error free afler transmission over 88km SMF, validating the fea- sibility of the optical FSK labeling scheme. References 1. D. J. Blumenthal et al, "All-optical label swap- p h g  networks and technologies," J. Lightwave 2. T. Koonen et al. "Oatical oacket routine in IP- Technal., ~18,2058-2075 (2000). over-WDM netw&dep&ng tw&veioptical labelline," THL2.1, ECOC'OI (2001). 3. N. chi et al,  all-optical transparent wave- length conversion of an optically labeled signal in ASWDPSK orthogonal modulation," LEOS'02, MF3. (20021. 4. M; Hick& and L. Kazavsky, "Combined fre- quency and amplitude modulation for the STAR- NET WDM computer communication network," IEEE Photon. Technol. Lett., Y 6, 1473-1475 (1994). 5 .  R. S. Vodhanel et al, "Performance of directly modulatcd DFB lasers in l0Gbls ASK/FSW DPSK lightwave systems," J. Lightwave Tech- nol., "8, 1379-1385 (1990). TuR 4:30 PM - 6:OO PM Murphy 1 Aceess Networks 1 Gordon Wilson, Oneno Inc., USA, Presider TuRl (Invited) 4:30 PM Whatever Happened to Fiber-to-the-Home? N. Frigo, K. Reichmann, P. lannone, AlTLabs..  Middletown, NJ. Email:fiigo@otr.com. The early vision of FTTH, which promised abun- dant, ubiquitous, and future-proof bandwidth to consumers, has remained largely unrealized nearly 20 years after its birth. We discuss the his- torical, competitive, economic, and Service rea- sons for this and prospects for the future. Introduction The vision of Fiber-to-the-Home (FTTH) was developed in the 1980's to satisfy the perceived need for future consumer applications. Optical fiber, it was felt, would permit high bandwidth transport, remove "bottlenecks" as video-rich ser- vices were developed, enable upgrades, and per- mit passive multiplexing that would remove remote powering costs. Various aspects of its his- t o n  have been reviewed [I-31. In today's terms, applications such as telephony and video-on- demand were to be carried over a B-ISDN univer- sal carrier at OC-3 rates [I]. Proposals included an optical version of the telephony loop (each fiber carrying one house's circuit) to passive opti- cal networks (PONS) with an optical splitler delivering light (and bandwidth) to several optical network units (ONUS). For Fiber-la-the-Curb (FTTC), the ONUS served several homes. In the nearly two decades since the FTTHIC vision was established, economic, regulatory, and technolog- ical forces have frustrated the vision's intended universal implementation. The Recent Past Fig. 1 shows some of the structural forces at work. The WO major consumer applications today are broadcast television and telephony, which have nearly opposite characteristics. TV is a pas- sive impersonal entertainment delivered as a ane- way service requiring high bandwidth. Telephony is personal communication that requires a two- way symmetric, low-bandwidth connection. We apparently value communication more than ''con- tent" [4] because the cost we pay per bit of infor- mation on phone calls exceeds that of entertainment by 6 or 7 orders of magnitude. W S  infrastructure is largely coaxial cable, with Multi- ple System Operaton (MSOs) as service provid- en, while telephony is largely delivered over twisted wire pairs by Incumbent Local Exchange Carriers (ILECs). The two-way naNre and qualily of telephony makes aggregation, multiplexing, and switching essential, and thus the telephone and TV physical networks look quite different. Both the MSOs and the ILECs have, over time, created efficient networks, and they can be viewed as vertically integrated: they own the net- works that deliver their services. Both entities saw potential markets in the intermediate area of Fig. 1, labeled "Data," which could provide personal- ized entertainment, be consumed as an end in itself, or enhance communications services. This seemed a natural extension for the ILECs, since these services required point-to-point cannec- lions, while regulatory and technical reasons pre- vented MSOs from entering. This space was intended for FTTH: the services would need more bandwidth than the capper plant allowed, and would need a new architecture, but revenues from new services such as Video an Demand (VOD) were expected to support a fiber build-aut[l]. Developments in the 1980s, however, changed the landscape dramatically. Advances in linear light- wave technology enahled CATV trunks with cas- caded amplifiers to be replaced with high bandwidth, high fidelity optical analog transmis- sion links to local nodes. The "pushing fiber deeper" approach became known as "Hybnd Fiber-Coax" (HFC), which, with its ability to shrink serving area sizes [SI, began IO look like the telco's FTTWC plans, would permit the MSOs to carry data (albeit on a shared medium). This would crowd into the telcos' vision and could lead to competition in that new space. Meantime, technical advances in data compres- sion reduced the information needed to carry video by nearly two orders of magnitude, and new modems with a variety ofDigital Subscriber Loop (nDSL) formats were developed to cany  data and video over copper pairs. Finally, user-friendly graphical interfaces made world-wide web traffic explode (making that central area in Fig. I look more attractive), launched the dot-com boom and CLEC threats. Technical advances also made Sat- ellite TV a credible threat to cable, and Wireless phones a threat 10 landlines. Thus, technical progress and regulatory relaxations set the stage for that middle area to be actively contested, while putting pressure on each market. What does the future hold? Prospects far the Future Overriding all of the plans, of course, is the need for the network lo make money for its a m &  early advocates estimated that the customerk willingness to pay far phone and VOD services would support a cost of $1500 per subscriber for lnfiastructure [I], which is still B reasonable guesi today. Much activ- ity in fora and standards p u p s  such as the Full Ser- vice Access Network ( F S A N )  and Ethemet in the First Mile (EFM) activities suppart the vision, and vendors a~ within s&g m g e  of these costs. Fur- thermore, lhere are several large mals run by UECs (dadng back to the 1980's), and some MSO rials have recently begun, so the player, M developing technological experience. What M the prospects for a massive FTTH rollout? We believe that a major deployment is unlikely far the foreseeable fum for several reasons. First, the cost calculations require essentially monopoly conditions The major cost of the FTTH network is in the installation of ubiquitous distri- bution fiber that permits a drop to any potential customer. This fixed cost of passing every cus- tomer must be bome by that fraction of customers who actually subscribe. If the "take rate" in a compaitive market is 25%, far example, then the effective cost per customer is nearly 4 times the Authorized licensed use limited to: Danmarks Tekniske Informationscenter. Downloaded on March 03,2010 at 10:34:51 EST from IEEE Xplore.  Restrictions apply. 

A novel optical labeling scheme using a FSK modulated DFB laser integrated with an EA modulator

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A novel optical labeling scheme using a FSK modulated DFB laser integrated with an EA modulator

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