Danielsen, Søren Lykke

Hansen, Peter Bukhave

Jørgensen, Carsten

Mikkelsen, Benny

Poulsen, Henrik Nørskov

Stubkjær, Kristian

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Downloaded from orbit.dtu.dk on: Dec 17, 2017Wavelength Converters: Network Applications And Systems ExperimentsDanielsen, Søren Lykke; Jørgensen, Carsten; Mikkelsen, Benny; Hansen, Peter Bukhave; Poulsen,Henrik Nørskov; Stubkjær, KristianPublished in:Lasers and Electro-Optics, 1997. CLEO '97., Summaries of Papers Presented at the Conference onPublication date:1997Document VersionPublisher's PDF, also known as Version of recordLink back to DTU OrbitCitation (APA):Danielsen, S. L., Jørgensen, C., Mikkelsen, B., Hansen, P. B., Poulsen, H. N., & Stubkjær, K. (1997).Wavelength Converters: Network Applications And Systems Experiments. In Lasers and Electro-Optics, 1997.CLEO '97., Summaries of Papers Presented at the Conference on (Vol. 11). IEEE.26 / CLE0’97 / MONDAY MORNING Electro-Vphcs, Vol. 8,1994 OSA I echnical 5 S J B. Yoo, C Caneau, R Bhat, M.A. 10‘ 10’ a 106 E L 10’ Digest Series (Optical Society of America, Washington, DC, 1994), paper CThD6. Koza, A Rajhel, N Antoniades, Appl. lnputs,g + Phys. Lett. 68,2609 (1996) g 6. S. J. B. Yoo, R. Bhat, C. Cancau, M. A. Kom, Appl. Phys. Lett. 66,741 0 ( J  995). CMF4 (Invited) 9:30 am Wavelength converters: network applications and systems experiments MI wavelength convener -40 -35 -3 0 -25 Received power (dBm) fa\ \-, S. L. Danielsen, C. Joergensen, B. Mikkelsen, P. B. Hansen, H. N. Poulsen, K. E. Stubkjaer, Center for Broadband Telecommunications, Dept. of Electromagnetics Systems, Technical University of Denmark, Building 348, DK-2800 Lyngby, Denmark; E-mail: sld@emi.dtu.dk Wavelength converters will be implemented in future wavelength-division multiplexing (WDM) networks to improve the efficiency, throughput, and flexibility of the network. The converters will reduce wavelength blocking and allow for a distributed wavelength assign- ment that relaxes the management as well as -20 -15 -LO -5 0 5 10 15 0 10 20 30 40 SO 60 Input power, 1543 nm (dBm) Time (ps) - eases the reconfiguration and protection of the network. Many research projects such as the ARPA MONET project therefore con- sider the use of wavelength converters and within the European ACTS research program both KEOPS and OPEN include wavelength converters in their switch block architectures. An example of a switch architecture with wavelength converters is given in Fig. 1. The advantage of using the converters to avoid wavelength blocking at the switch output is illustrated in the figure. The above example underlines the impor- tance of developing efficient and practical all- optical wavelength converters. To be attractive for future networks the converters must fulfd a number of requirements: they should be bit- Erlang load per wavelewgh channel CMF4 Fig. 1 Top: Schematic of WDM switch block with wavelength converters. Bottom: Influ- ence of wavelength conversion on the blocking probability of a 16 X 16 WDM cross-connect (N = 16) with the number of wavelength chan- nels, n, as the parameter. CMF4 Fig. 2 (a) Wavelength conversion principle using MZI and MI structures with SOAs. (b) Static transfer function of the MZI converter: Output power at h,,,, = 1535 nm versus input power at h, = 1543 nm. The bias current to SOAl is 300 mA and 196 mA to SOM. rate transparent, polarization- and wavelength- independent, give high extinction and signal-to- ASE ratios for the converted signals and only introduce a small chup. Many useful techniques have been proposed and demonstrated; the most promising of these are based on cross-gain modulation (XGM) and cross-phase modula- tion (XPM) in SOAs and lasers. The advantages of XGM conversion is discussed but the re- minder of the attention is on SOA-based XPM converters because of their superior perfor- mance. These converters rely on the modulation of the refractive index of SOAs placed in inter- ferometric structures such as Michelson (MI) and Mach-Zehnder interferometers (MZI) [see Fig. 2(A)]. The semiconductor optical amplifiers hereby operate as phase shifters, which enables efficient wavelength conversion as described in Ref. 1. A static transfer characteristic is shown in Fig. Z(B) for a polarization-independent MZI made by Thomson-CSF in France. XPM interferometric converters feature very high extinction ratios for the converted signals as well as wavelength independence and potentially also polarization indepen- dence and small chirp. The chirp introduced by XPM conversion even supports transmis- sion over nondispersion-shifted fiber allowing transmission beyond the dispersion limit. Given the above mentioned features, recent research has been devoted to the development of high-speed XPM converters (>IO Gbit/s). High speed can be obtained by using high in- put powers and high injection currents. Addi- tionally, theoretical and experimental studies have shown that a high optical confinement factor and high differential gain for the SOAs (b) CMF4 Fig. 3 (a) BER performance of 20 Gbit/s wavelength conversion from 1555-1560 nm using an all-active MQW Michelson con- verter. Power levels are: h,,,, = 1560 nm, 9 dBm, X, = 1555 nm, 6 dBm. (b) 40 Gbitis converted eye-diagram with an all-active MQW Michelson converter. Conversion from 1558-1562 nm is carried out. Power levels are: X,,,, = 1562 nm, 9 dBm, X, = 1558 nm, 8 dBm. will enable high bit-rate operation. As a fine example of this, Alcatel has fabricated a com- pact (1.3 mm long) monolithically integrated Michelson chip using all-active multiple quan- tum well based layer structures that has dem- onstrated excellent performance at both 20 and 40 Gbit/s as shown in Fig. 3. Extinction ratios above 10 dB are easily reached at these high bit-rates together with signal-to-ASE ra- tios exceeding 25 dB (1-nm bandwidth), which is of great importance for the cascadability. Issues of controllability of the converters are also addressed. 1. T. Duress et al., IEEE J. Lightwave Tech- nol. 1 4  (1996). Authorized licensed use limited to: Danmarks Tekniske Informationscenter. Downloaded on March 09,2010 at 09:34:47 EST from IEEE Xplore.  Restrictions apply. 

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