1. Josef Vojtěch, Miroslav Karásek, Jan Radil www.ces.net ALL-OPTICAL CHROMATIC DISPERSION COMPENSATION IN LONG-HAUL TRANSMISSION OVER 225km – WITH NO INLINE AMPLIFICATION

2. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 2 All-optical chromatic dispersion compensation Outline Motivations CD compensation techniques Laboratory setup Experimental results Conclusions Q & A

3. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 3 Majority of installed fibres – ITU-T G.652, SSMF Designed for operation in O band C band – attractive area of operation (low IL, EDFAs, …) CD coefficient around 1550 nm ≈ 16.8 ps/(nm * km) CD limits reach significantly 10G NRZ - 90 km of SSMF 40G NRZ - 5 km of SSMF 100G NRZ - 900 m of SSMF !!! Must be mitigated or compensated All-optical chromatic dispersion compensation Motivations I

4. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 4 CD management studied intensively in regular setups All-optical chromatic dispersion compensation Motivations II 80 km SSMF DCF 80 km SSMF In Research and Educational Networks sometimes not possible or economically reasonable have active components between the transmitter and the receiver Nothing-in-line (NIL) approach CD compensation in long-haul NIL setups – relatively unknown

5. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 5 1G NIL 300 km G.652 (EDFA only) 325 km G.652 (EDFA + Raman) 10G NIL 2x10G+2x1G WDM 202km G.652 (EDFA + DCF) 8x10G DWDM 250km G.652 (EDFA + FBGs) 10G DWDM 302 km G.655+652 (EDFA + Raman) 10G NIL bidirectional (single fibre) transmission 2x4x10G 210km G.652 (EDFA + FBGs) All-optical chromatic dispersion compensation Motivations II – NIL results

6. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 6 Electrical pre or/and post processing All-optical compensating elements: All-optical chromatic dispersion compensation CD compensation Dispersion compensating fibre (DCF) Fibre Bragg grating (FBG) Gires-Tournois etalon (GTE) Virtually-imaged phase-array (VIPA)

7. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 7 All-optical chromatic dispersion compensation All-optical compensating elements comparison Broad- band IL [dB]TunableSlope match DCF 16kmYES8.9SemiNO FBGNO2.9YES FBGYES3.5NOYES GTENO2YESNO GTEYES7NOYES VIPANO7YESNO * Elements compensating CD of 100 km SSMF are compared ** Table based on product information known to authors

8. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 8 TX - 8 x 10 GE DWDM XFPs 1550.12 - 1556.55 nm 225 km of SSMF on reels (granularity 50 km and 25 km) CD  +3780 ps/nm Four DCF modules -1370, -946, -689 and -343 ps/nm Packet error rate measured by Packet Blazer 10GigE FTB-5810G All-optical chromatic dispersion compensation Lab setup I – DCF based Tx 1...... Tx 8 Rx 1 Rx 8...... MUXMUX DEMUXDEMUX DCF 225 km of SSMF Booster EDFAPreamp EDFAs

9. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 9 Compensated value -3400 ps/nm,  90% of line CD Channelized fixed FBGs Chanelized tuneable FBGs Broadband fixed FBGs Channelized tuneable GTEs All-optical chromatic dispersion compensation Lab setup II – alternative elements 225 km of SSMF Booster EDFAPreamp EDFA Tx 1...... Tx 8 Rx 1 Rx 8...... MUXMUX DEMUXDEMUX CD

10. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 10 Back-to -back eye-diagram of transmitter All-optical chromatic dispersion compensation Lab setup cont.

11. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 11 T olerance to composite l aunched power – post compensation All-optical chromatic dispersion compensation Experimental results - DCFs

12. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 12 T olerance to composite l aunched power – pre compensation 9% All-optical chromatic dispersion compensation Experimental results - DCFs

13. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 13 Tolerance to composite l aunched power – pre compensation 18 and 25 % All-optical chromatic dispersion compensation Experimental results - DCFs

14. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 14 Tolerance to composite l aunched power – post compensation All-optical chromatic dispersion compensation Experimental results – alternative elements

15. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 15 Tolerance to composite l aunched power – post compensation All-optical chromatic dispersion compensation Experimental results – broadband FBGs

16. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 16 Tolerance to composite l aunched power – post compensation All-optical chromatic dispersion compensation Experimental results – channelized FBGs

17. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 17 Tolerance to composite l aunched power – post compensation All-optical chromatic dispersion compensation Experimental results – channelized GTEs

18. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 18 Tolerance to c ompensation ratio – post compensation All-optical chromatic dispersion compensation Experimental results – tunable elements

19. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 19 Influence of post compensation ratio - TCGTEs All-optical chromatic dispersion compensation Experimental results – tunable elements 79 % 85% 90%

20. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 20 Tolerance to c ompensation ratio – pre compensation 9% All-optical chromatic dispersion compensation Experimental results – tunable elements

21. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 21 Tolerance to compensation ratio – pre compensation 9% All-optical chromatic dispersion compensation Experimental results – tunable elements TCGTEs - 71% post compensationTCFBGs - 71% post compensation

22. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 22 Tolerance to compensation ratio – pre compensation 18% All-optical chromatic dispersion compensation Experimental results – tunable elements

23. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 23 All-optical chromatic dispersion compensation Conclusions - DCFs Post compensation - error free transmission in quite small range (about 60 – 70%) Small pre compensation 9% - error free transmission range grows to (about 54 - 79%) Further increase of pre compensation – lower power threshold of error free operation but decreases power range significantly

24. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 24 All-optical chromatic dispersion compensation Conclusions – alternative elements GTEs allow lower launched input powers Broadband FBGs easily handle high launched powers Both fixed and tuneable channelized FBGs perform nearly identically; tuneable ones a little worse due to higher IL Small pre compensation 9% - error free transmission range grows significantly again

25. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 25 All-optical chromatic dispersion compensation Conclusions DCFs - well known, widely deployed and broadband but bulky, lossy, prone to non-linear effects and expensive FBGs - commercially available, lower IL, broadband (some), tunable (some), cost effective GTEs - very low IL, tunable, cost effective but not so widespread and available VIPAs - not tested yet, commercial availability limited Next challenge CD compensation at 40G

26. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 26 All-optical chromatic dispersion compensation Acknowledgement Lada Altmanová Jan Gruntorád Stanislav Šíma This research has been supported by the Ministry of Education, Youth and Sport of the Czech Republic under research plan no. MSM6383917201 called “Optical National Research Network and Its New Applications”.

27. Aug 29, 2007 CSN 2007 Palma de Mallorca, Spain 27 All-optical chromatic dispersion compensation Thank you for your kind attention! Q&A