Josef Vojtěch, Miroslav Karásek, Jan Radil
www.ces.net
ALL-OPTICAL CHROMATIC DISPERSION COMPENSATION IN LONG-HAUL TRANSMISSION OVER 225km –
WITH NO INLINE AMPLIFICATION
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
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
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 DCF 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
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
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)
Aug 29, 2007 CSN 2007
Palma de Mallorca, Spain 7
All-optical chromatic dispersion compensation
All-optical compensating elements comparisonBroad-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
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
Tx1
.
.
.
Tx8
Rx1
Rx8
.
.
.
MUX
DEMUX
DCF DCF225 km of SSMF
Booster EDFA Preamp EDFAs
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 EDFA Preamp EDFA
Tx1
.
.
.
Tx8
Rx1
Rx8
.
.
.
MUX
DEMUX
CD
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.
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Palma de Mallorca, Spain 11
Tolerance to composite launched power – post compensation
All-optical chromatic dispersion compensation
Experimental results - DCFs
Launched power tolerance post comp. only
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
20 21 22 23 24 25 26 27 28 29 30
Composite Pin [dBm]
Lo
g o
f fr
am
e e
rro
r ra
te
89%
79%
70%
61%
54%
Aug 29, 2007 CSN 2007
Palma de Mallorca, Spain 12
Tolerance to composite launched power – pre compensation 9%
All-optical chromatic dispersion compensation
Experimental results - DCFs
Launched power tolerance - precomp. ratio 9%
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
20 22 24 26 28 30
Composite power in [dBm]
Lo
g o
f fr
am
e e
rro
r ra
te
pr 9% po 79%
pr 9% po 61%
pr 9% po 54%
Aug 29, 2007 CSN 2007
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Tolerance to composite launched power – pre compensation 18 and 25 %
All-optical chromatic dispersion compensation
Experimental results - DCFs
Launched power tolerance - precomp. ratio 18, 25%
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
20 22 24 26 28 30
Composite Pin [dBm]
Lo
g o
f fr
am
e e
rro
r ra
te
pr 18% po 70%
pr 18% po 61%
pr 25% po 64%
pr 25% po 54%
Aug 29, 2007 CSN 2007
Palma de Mallorca, Spain 14
Tolerance to composite launched power – post compensation
All-optical chromatic dispersion compensation
Experimental results – alternative elements
Launched power tolerance
-10
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
20 22 24 26 28 30
Composite Pin [dBm]
Lo
g o
f fr
ame
erro
r ra
te
chann. FBG
chann. TFBG
broadband FBG
GTE
Aug 29, 2007 CSN 2007
Palma de Mallorca, Spain 15
Tolerance to composite launched power – post compensation
All-optical chromatic dispersion compensation
Experimental results – broadband FBGs
Launched power tolerance
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
21 22 23 24 25 26 27 28 29 30
Composite Pin [dBm]
Lo
g o
f fr
ame
erro
r ra
te
BFBG 79%
BFBG 90%
BFBG 97%
Aug 29, 2007 CSN 2007
Palma de Mallorca, Spain 16
Tolerance to composite launched power – post compensation
All-optical chromatic dispersion compensation
Experimental results – channelized FBGs
Launched power tolerance
-9-8-7-6-5-4-3-2-10
21 23 25 27 29
Composite Pin [dBm]
Log
of fr
ame
erro
r ra
te
CFBG 79%
CFBG 85%
CFBG 90%
Aug 29, 2007 CSN 2007
Palma de Mallorca, Spain 17
Tolerance to composite launched power – post compensation
All-optical chromatic dispersion compensation
Experimental results – channelized GTEs
Launched power tolerance
-9-8-7-6-5-4-3-2-10
21 23 25 27 29
Pin [dBm]
Log
of fr
ame
erro
r ra
te
CGTE 79%
CGTE 85%
CGTE 90%
Aug 29, 2007 CSN 2007
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Tolerance to compensation ratio – post compensation
All-optical chromatic dispersion compensation
Experimental results – tunable elements
Post compensation
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
60% 65% 70% 75% 80% 85% 90% 95% 100%
CD compensation [ps/nm]
Lo
g o
f fr
ame
erro
r ra
te
TCFBG
TCGTE
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%
Aug 29, 2007 CSN 2007
Palma de Mallorca, Spain 20
Tolerance to compensation ratio – pre compensation 9%
All-optical chromatic dispersion compensation
Experimental results – tunable elements
Pre compensation 9 %
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
60% 65% 70% 75% 80% 85% 90% 95% 100%
CD compensation [ps/nm]
Lo
g o
f fr
am
e e
rro
r ra
te
TCFBG
TCGTE
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 compensation TCFBGs - 71% post compensation
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
Pre compensation 18%
-9
-8
-7
-6
-5
-4
-3
-2
-1
0
60% 65% 70% 75% 80% 85% 90% 95% 100%
CD compensation [ps/nm]
Lo
g o
f fr
am
e e
rro
r ra
te
TCFBG
TCGTE
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
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
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
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”.
Aug 29, 2007 CSN 2007
Palma de Mallorca, Spain 27
All-optical chromatic dispersion compensation Thank you for your kind attention!
Q&A