Josef Vojtech, Miroslav Kar

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ALL-OPTICAL CHROMATIC DISPERSION COMPENSATION IN
LONG-HAUL TRANSMISSION OVER 225km WITH NO
INLINE AMPLIFICATION
www.ces.net

• Josef Vojtech, Miroslav Karásek, Jan Radil

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All-optical chromatic dispersion
compensationOutline

• Motivations
• CD compensation techniques
• Laboratory setup
• Experimental results
• Conclusions
• Q A

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All-optical chromatic dispersion
compensationMotivations I

• 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

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All-optical chromatic dispersion
compensationMotivations II

• CD management studied intensively in regular
  setups

• 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

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All-optical chromatic dispersion
compensationMotivations II NIL results

• 1G NIL
• 300 km G.652 (EDFA only)
• 325 km G.652 (EDFA Raman)
• 10G NIL
• 2x10G2x1G WDM 202km G.652 (EDFA DCF)
• 8x10G DWDM 250km G.652 (EDFA FBGs)
• 10G DWDM 302 km G.655652 (EDFA Raman)
• 10G NIL bidirectional (single fibre) transmission
• 2x4x10G 210km G.652 (EDFA FBGs)

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All-optical chromatic dispersion compensationCD
compensation

• Electrical pre or/and post processing
• All-optical compensating elements

• Dispersion compensating fibre (DCF)
• Fibre Bragg grating (FBG)
• Gires-Tournois etalon (GTE)
• Virtually-imaged phase-array (VIPA)

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All-optical chromatic dispersion compensation
All-optical compensating elements comparison
Broad-band IL dB Tunable Slope match
DCF 16km YES 8.9 Semi NO
FBG NO 2.9 YES YES
FBG YES 3.5 NO YES
GTE NO 2 YES NO
GTE YES 7 NO YES
VIPA NO 7 YES NO
Elements compensating CD of 100 km SSMF are
compared Table based on product information
known to authors
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All-optical chromatic dispersion
compensationLab setup I DCF based
225 km of SSMF
DCF
DCF
Booster EDFA
Preamp EDFAs

• 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

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All-optical chromatic dispersion
compensationLab setup II alternative elements
225 km of SSMF
Booster EDFA
Preamp EDFA

• Compensated value -3400 ps/nm, ? 90 of line CD
• Channelized fixed FBGs
• Chanelized tuneable FBGs
• Broadband fixed FBGs
• Channelized tuneable GTEs

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All-optical chromatic dispersion
compensationLab setup cont.
Back-to -back eye-diagram of transmitter
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All-optical chromatic dispersion
compensationExperimental results - DCFs
Tolerance to composite launched power post
compensation
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All-optical chromatic dispersion
compensationExperimental results - DCFs
Tolerance to composite launched power pre
compensation 9
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All-optical chromatic dispersion
compensationExperimental results - DCFs
Tolerance to composite launched power pre
compensation 18 and 25
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All-optical chromatic dispersion
compensationExperimental results alternative
elements
Tolerance to composite launched power post
compensation
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All-optical chromatic dispersion
compensationExperimental results broadband
FBGs
Tolerance to composite launched power post
compensation
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All-optical chromatic dispersion
compensationExperimental results channelized
FBGs
Tolerance to composite launched power post
compensation
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All-optical chromatic dispersion
compensationExperimental results channelized
GTEs
Tolerance to composite launched power post
compensation
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All-optical chromatic dispersion
compensationExperimental results tunable
elements
Tolerance to compensation ratio post
compensation
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All-optical chromatic dispersion
compensationExperimental results tunable
elements
79
90
85
Influence of post compensation ratio - TCGTEs
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All-optical chromatic dispersion
compensationExperimental results tunable
elements
Tolerance to compensation ratio pre
compensation 9
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All-optical chromatic dispersion
compensationExperimental results tunable
elements
TCGTEs - 71 post compensation
TCFBGs - 71 post compensation
Tolerance to compensation ratio pre
compensation 9
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All-optical chromatic dispersion
compensationExperimental results tunable
elements
Tolerance to compensation ratio pre
compensation 18
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All-optical chromatic dispersion
compensationConclusions - 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

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All-optical chromatic dispersion
compensationConclusions 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

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All-optical chromatic dispersion
compensationConclusions

• 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

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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.

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All-optical chromatic dispersion compensation
Thank you for your kind attention!QA