Clausen, Anders

Jeppesen, Palle

Oxenløwe, Leif Katsuo

Seoane, Jorge

Siahlo, Andrei

Demultiplexing of a 640 Gb/s single-polarization optical time-division multiplexed (OTDM) signal and a 640 Gb/s signal with two alternating polarizations transmitted through 77 km of non-zero dispersion shifted fiber (NZDSF) are realized using a non-linear optical loop mirrors (NOLM) based on 500 m of highly non-linear fiber (HNLF)

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Downloaded from orbit.dtu.dk on: Dec 17, 2017640 Gb/s OTDM Transmission and Demultiplexing using a NOLM with CommerciallyAvailable Highly Non-linear FiberSiahlo, Andrei; Clausen, Anders; Oxenløwe, Leif Katsuo; Seoane, Jorge; Jeppesen, PallePublished in:Conference on Lasers and Electro-Optics, 2005. (CLEO).Publication date:2005Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Siahlo, A., Clausen, A., Oxenløwe, L. K., Seoane, J., & Jeppesen, P. (2005). 640 Gb/s OTDM Transmission andDemultiplexing using a NOLM with Commercially Available Highly Non-linear Fiber. In Conference on Lasersand Electro-Optics, 2005. (CLEO). (Vol. 2, pp. 883-885). [CTuo1] IEEE.2005 Conference on Lasers & Electro-Optics (CLEO)CTuOl640 Gb/s OTDM Transmission and Demultiplexingusing a NOLM with Commercially AvailableHighly Non-linear FiberA.I. Siahlo, A.T. Clausen, L.K. Oxenl0we, J. Seoane, P. JeppesenCOM Center, Technical University of Denmark, DTU-Building 345V, DK-2800 Lyngby, Denmnarkans@com.dtu.dkAbstract: Demultiplexing of a 640 Gb/s single-polarization OTDM signal and a 640 Gb/s signalwith two alternating polarizations transmitted through 77 km of NZDSF are realized using aNOLM based on 500 m of HNLF.©2005 Optical Society of AmericaOCIS codes: (060.45 10) Optical communications (060.2360) Fiber optics links and subsystems1. IntroductionThe interest in ultra-high speed optical time-division multiplexed (OTDM) transmission systems has steadilyincreased over the last few years [1-9]. In OTDM systems fast switches are essential. Electrical drivenElectroabsorption modulators (EAM) are convenient for demultiplexing from 160 to 40 Gb/s [2,3], but usually not athigher bit rates. Recently though, 320 Gb/s demultiplexing using semiconductor components were demonstrated[4,5] in the forms of a fast photodiode integrated with a traveling-wave EAM [4], and a Mach-Zehnderinterferometer with semiconductor optical amplifiers [5]. However, all-optical switches based on Non-linear OpticalLoop Mirrors (NOLM) remain the devices applicable for demultiplexing from 640 Gb/s [6,7].The switching window in a NOLM-based demultiplexer is determined by the width of the control pulses and thewalk-off between the control pulse and the data signal. To reduce walk-off, carefully matching fiber segments [6] oradvanced fibers with increased non-linear coefficients [8] have been used in NOLMs.In this paper we report on a 640 Gb/s experiments using a NOLM with a single piece of commercially availableHighly Non-linear Fiber (HNLF) with careful optimized dispersion design. Successful demultiplexing of a 640 Gb/sAlternating Polarization OTDM (AP-OTDM) signal in complete transmission setup and a back-to-backdemultiplexing of a 640 Gb/s Single Polarization OTDM (SP-OTDM) signal are realized. Recently we demonstrateddemultiplexing of all OTDM channels after transmission of a 320 Gb/s single-polarization OTDM signal throughspans containing continuous fiber of 80 km [9]. In this paper transmission of 640 Gb/s through continuous 77 km ofnon-zero dispersion shifted fiber (NZ-DSF) is realized for the first time.2. Experimental set-up 640 Gb/s AP-OTDMThe experimental set-up for 640 Gb/s AP-OTDM is shown in Fig. l,a. The pulse source in the transmitter (TX) is anErbium Glass Oscillator Pulse Generating Laser (ERGO-PGL) emitting 1.5 ps pulses at the wavelength of 1557 nmat a 10 GHz repetition rate. The pulse stream is modulated with a 27-1 to 23_-l 10 Gb/s Pseudo Random BitSequence using a Mach-Zehnder modulator (MZ). The 10 Gb/s data stream is multiplexed to 320 Gb/s using a 27-lPRBS properties maintaining and polarization maintaining fiber-based multiplexer and to 640 Gb/s using twopolarization-controllers, a polarization-coupler and a delay line.Demultiplexing to 10 Gb/s in the receiver (RX) is based on a NOLM constructed with 500 meters of HNLF asthe non-linear element. A polarizer and a polarization controller are situated in front of the NOLM to ensurepolarization demultiplexing from AP-640 Gb/s to 320 Gb/s. The HNLF has a zero-dispersion wavelength of1551 nm, a dispersion slope of 0.016 ps/(nm2km) and a non-linear coefficient of 10.5 W-tkm-1. The short pulses withrepetition of 10 GHz from the second ERGO-PGL at 1541 nm are applied to the NOLM as a control signal. Sincethe zero-dispersion wavelength is between the wavelengths of the data and control, the walk-off is minimized. Theperformance of the system is evaluated using a pre-amplified 10 Gb/s receiver including an error detector.As the impact of interferometric crosstalk is reduced for AP-OTDM systems, no additional pulse compressionfor the data and the control signal is required, thus reducing the complexity of the set-up.A complete transmission system is realized for the 640 Gb/s AP-OTDM. The transmission span is 77 kmNZDSF compensated by 3 km Dispersion Compensating Fiber (DCF). The accumulated dispersion of the span isless than 0.4 ps/nm in the magnitude at 1557±3 nm. The input power of the data signal to the transmission span is8 dBm. For the transmitted optical clock, a light of a continuous-wave laser (CW) at 1548 nm was sinusoidally883Authorized licensed use limited to: Danmarks Tekniske Informationscenter. Downloaded on December 2, 2009 at 04:12 from IEEE Xplore.  Restrictions apply. 2005 Conference on Lasers & Electro-Optics (CLEO)CTuOl(a)(b)$ UNl§ 2 LJL ) Pulse NOLM15k i 1.si4nm DDF0O8Ps compressionPulse compression E..rr_ _-- M etcorFig. 1. a) 640 Gb/s system with two alternating polarizations (640 Gb/s AP-OTDM set-up); b) 640 Gb/s system with onepolarization (640 Gb/s SP-OTDM set-up)modulated by a MZ. The data and clock signals are combined before transmission and separated by filtering aftertransmission. The NZDSF and HNLF are kindly provided by OFS Denmark.3. Experimental set-up 640 Gb/s SP-OTDMIn Fig. l,b the set-up for SP-OTDM 640 Gb/s is shown. This is a modified version of the set-up shown in Fig. 1,a.As opposed to the AP-OTDM, the impact of interferometric crosstalk between the pulses increases and significantlynarrower pulses are required for both data and control pulses. In the 640 Gb/s SP-OTDM set-up both data andcontrol pulses are compressed in the following way: the 1.5 ps pulses are amplified by a high-power erbium-dopedfiber amplifier (HP-EDFA), then broadened by 1.4 nm filters to 2.5 ps and injected into I km of dispersiondecreasing fiber (DDF). The width of the compressed pulses of both data and control signals is 0.8 ps. For the640 Gb/s SP-OTDM set-up the multiplexer is a PRBS and polarization maintaining fiber delay line structure. TheRX is similar in the two set-ups, except that the polarization demultiplexer in front of the NOLM has been removed.4. Characterizations and resultsThe autocorrelation traces of the 320 Gb/s data signal based on 0.8 ps pulses, the 640 Gb/s signal based on 0.8 ps(b)time [ps]1540 1550 1560wavelength [nm](c)time [ps]Fig. 2. a) Autocorrelation traces of the 320 Gb/s and 640 Gb/s data signals. b) The spectrum at the input to the HNLF in the NOLM for the640 Gb/s AP and SP set-ups. c) Autocorrelation traces of the control signal and the switching window884C:0'oI000aJAuthorized licensed use limited to: Danmarks Tekniske Informationscenter. Downloaded on December 2, 2009 at 04:12 from IEEE Xplore.  Restrictions apply. 2005 Conference on Lasers & Electro-Optics (CLEO)CTuOlpulses and the 320 Gb/s signal based on 1.5 ps pulses are shown in Fig.2,a. The autocorrelation traces of themultiplexed data show that the time separation between the pulses is ample to resolve different OTDM channels.Fig.2,b shows the spectra of the control and data signals injected to the HNLF of the NOLM in the AP and SP640 Gb/s set-ups. The spectra show a very small overlapping between control and data signals.Fig.2,c shows the switching window of the NOLM in the 640xl Gb/s set-up. To evaluate the switchingwindow, CW light at data wavelength was injected in to the NOLM instead of the data. A control signal with apulsewidth of 0.8 ps (1.12 ps on autocorrelator) results in the switching window of 1.15 ps (1.59 ps onautocorrelator) which is acceptable for demultiplexing from 640 to 10 Gb/s. The switching window is slightlybroader than the control signal because of the walk-off between the control and data wavelengths in the NOLM.Fig. 3 shows the BER performance of the 640 Gb/s AP- and SP- set-up as a function of the input power to thepre-amplified receiver. In the 640 Gb/s AP set-up without transmission (b-b) polarization demultiplexing gives only1 dB penalty compared to 320 Gb/s with a single polarization. Transmission introduces a penalty of 5 dB. Thedifferent OTDM channels have similar performances and the difference between the sensitivity of the differentOTDM channels does not exceed 3 dB. The demultiplexing from 640 to 10 Gb/s in 640 Gb/s SP system shows anerror floor due to walk-off and the resultant relatively wide switching window and gives a penalty of 12.5 dBcompared to the 10 Gb/s back-to-back. Demultiplexing of the 320 Gb/s signal based on 0.8 ps pulses has a penaltyof 8 dB, emphasizing the challenge of using very narrow pulses.(a) (b)4 640 Trans., pol.chan.12 , ...640 Trans., pol.chan.2 2, 640:100 ~< 640 b-b, pol.chan.1 .*320:1 0'1 640 b-b, pol.chan.2t>' 640 b-b, pol.chan.2 x ( 10 Gb/s back-to-back4 x 0> 0 320Gb/sb-b 40 1_Cc x x10 Gb/s back-to-back ccw cCo 6 c°>,Z|o 65 Xo 8-o0 r ) 810 10I--40 -35 -30 -25 -40 -35 -30 -25receiver power [dBm] receiver power [dBm]Fig. 3. a) BER performance of demultiplexing after transmission for 640 Gb/s AP set-up,b) BER performance of demultiplexing for 640xl Gb/s SP set-up.4. ConclusionDemultiplexing of a 640 Gb/s OTDM signal is performed using a NOLM with a 500 m HNLF with carefullymanaged dispersion as the non-linear element. Transmission through 77 km of NZDSF of a 640 Gb/s signal withtwo polarizations and back-to-back demultiplexing of 640 Gb/s signal with single polarization are realized. Thedemultiplexing is successful and error-free for both systems.5. References1. European IST project TOPRATE IST-2000-286572. M. Schmidt, E. Lach, K. Schuh, M. Schilling, P. Sillard, G. Veith, "Unrepeatered 320 Gbit/s (8x40 Gbit/s) OTDM transmission over 80 kmTeraLightm fiber link", ECOC'03 (2003), paper We4-P.1 17.3. B. Mikkelsen, G. Raybon, R.-J. Essiambre, A.J. Stentz, T.N. Nielsen, D.W. Peckham, L. Hsu, L. Gruner-Nielsen, K. Dreyer and J.E. Johnson,"320-Gb/s single-channel pseudolinear transmission over 200 km of nonzero-dispersion fiber", IEEE Photonics Technology Letters, 12, 1400-1402 (2000).4. S. Kodama, T. Yoshimatsu, H. Ito, "320 Gbit/s error-free demultiplexing using ultrafast optical gate monolithically integrating a photodiodeand electroabsorption modulator", Electronic Letters, 39, 1269 -1270 (2003).5. A. Suzuki, X. Wang, Y. Ogawa, S. Nakamura, "10x320Gb/s (3.2Tb/s) DWDM/OTDM Transmission in C-band by Semiconductor-BasedDevices", ECOC'04 (2004), paper Th4.t.7.6. M. Nakazawa, T.Yamamoto, K.R. Tamura, "1.28 Tbit/s-70 km OTDM transmission using third- and fourth-order simultaneous dispersioncompensation with a phase modulator", Electronic Letters, 36, 2027 -2029 (2000).7. V. Marembert, C. Schubert, S. Ferber, K. Schulze, C. Schmidt-Langhorst, C. Boemer, M. Kroh, R. Ludwig, S. Watanabe, F. Futami, R. Okabe,H.G. Weber, "Single-Channel 640 Gb/s DPSK transmission over a 160 km Fibre Link", ECOC'04 (2004), paper Th4.4.2.8. H. Sotobayashi, C. Sawaguchi, Y. Koyamada and W. Chujo, "Ultrafast walk-off-free nonlinear optical loop mirror by a simplifiedconfiguration for 320 Gb/s time-division multiplexing signal demultiplexing", Optics Lett., 27, 1555-1557, (2002).9 A.l. Siahlo, J. Seoane, A.T. Clausen, L.K. Oxenl0we, P. Jeppesen, "320 Gb/s Single-polarization OTDM Transmission over 80 km StandardTransmission Fiber", OFC'05 (2005).885Authorized licensed use limited to: Danmarks Tekniske Informationscenter. Downloaded on December 2, 2009 at 04:12 from IEEE Xplore.  Restrictions apply. 

640 Gb/s OTDM Transmission and Demultiplexing using a NOLM with Commercially Available Highly Non-linear Fiber

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640 Gb/s OTDM Transmission and Demultiplexing using a NOLM with Commercially Available Highly Non-linear Fiber

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