Post on 31-Mar-2015
No Dispersion Compensation 2000km NDSF Transmission of a 10Gb/s Signal using Microwave
Single-Sideband Multiplexing
2
Motivation
No chromatic dispersion compensation Avoids additional loss, cost and penalties No dispersion map issues
Residual dispersion Dispersion-nonlinearity interaction
No PMD compensation 400psec pulse is four times more tolerant to PMD
than 100psec pulse. Frequency stability
Tight spacing needs frequency stability Microwave LO’s are 10 times more stable
Microwave muxing is cheaper than 4 independent optical Tx
3
Outline
Baseband optical duobinary Experimental setup BER performance for distance OSNR requirement Effects of launch power-
Nonlinearity Conclusion
Baseband Optical Duobinary
-1 0 1 2 3 4 5
0 1 0 1 1 1
1 0 1 0 0 0
0 1 1 0 0 0 0
-V V V -V -V -V -V
0 V 0 -V -V -V
0 E 0 -E -E -E
0 1 0 1 1 1
Data
EXOR
Data
DataEncoder Out
LPF InLPF Out
Modulator Out
At receiver
Differential Encoder
Low pass filter
Modulator biased at
null
5
Low Pass Filtering
1
-1
0
• LPFing generates 3 level signal
6
Mapping at Modulator
Electric Field: E
Input Voltage
V
-V
E
E
Why duobinary propagates so well?
E
E
ISI cancels out
• ISI cancelation at zero • Low pass filtering and pulse shaping
• Spectrum is narrower• Narrowband filtering at receiver
1 0 1
8
Subcarrier Multiplexing
Baseband DEMUX
10Gb/s
2.5Gb/s
Upconverter
QuadratureHybrid
Laser
Dual Arm Modulator
Notch Filter
0˚90˚
• We only use the subcarrier channels at the receiver
9
Transmitter
15GHz
18GHz
6GHz
9GHz
Laser Mod Notch Filter Amplifier
90° Hyb
rid
90°
Hyb
rid
Σ
Σ
18GHz LO
AbsorptiveLPF
Up Converter Module
Center Block
• 9 and 18GHz channels are grouped
10
Phase Shift in Mixer
Mixer
Phase: π 0 π0…
0V
Local Oscillator
• Null biased mixer instead of null biased modulator
11
Group Delay of Absorptive Low-pass Filters
0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2600
650
700
750
800
850
900
950
1000
-16
-14
-12
-10
-8
-6
-4
-2
0
FLT1 GDFLT2 GDFLT1 ILFLT2 IL
Frequency [GHz]
Gro
up
Del
ay [
pse
c]
Ins
ert
ion
Lo
ss
[d
B]
12
Up Converter
Center Block
13
Link
6 or 10 100km spans
6 or 10 100km spans
Demux
Demux
2x1
EDFA
ASESource
VOA
OSA
OSA
14
Receiver
Decision threshold
bias
1x2
1x2
FPTunable
Filter
DCA
Power Meter
VOA
APD+TIA Limiting Amp
CDR Error Detector
15
Spectrum
• 18 GHz channel’s drive 800mVpp, Vpi 8V, MI 10%.
16
18 GHz Ch’s Performance
1.00E-08
1.00E-07
1.00E-06
1.00E-05
1.00E-04
1.00E-03
5 6 7 8 9 10 11 12 13 14 15
OSNR (dB)
BE
R
2000km
1200km
600km
0km
Confidential / ©2005 OpVista, Inc.
0 km
600 km 1200 km
2000 km
17
9 GHz Channels Performance
1.00E-08
1.00E-07
1.00E-06
1.00E-05
1.00E-04
1.00E-03
5 6 7 8 9 10 11 12 13 14 15
OSNR (dB)
BE
R
2000km
1200km
600km
0km
600 km 1200 km 2000 km
0 km
18
6 GHz Channel Performance
1.00E-08
1.00E-07
1.00E-06
1.00E-05
1.00E-04
1.00E-03
5 6 7 8 9 10 11 12 13 14 15
OSNR (dB)
BE
R
2000km
1200km
600km
0km
600 km 1200 km 2000 km
0 km
19
15 GHz Channel
1.00E-08
1.00E-07
1.00E-06
1.00E-05
1.00E-04
1.00E-03
5 6 7 8 9 10 11 12 13 14 15
OSNR (dB)
BE
R
2000km
1200km
600km
0km
0 km
600 km 1200 km 2000 km
20
2000 km Performance
1.00E-06
1.00E-05
1.00E-04
1.00E-03
7.0 8.0 9.0 10.0 11.0 12.0 13.0
OSNR (dB)
BE
R
18G
9G
6G
15G
• <1dB OSNR deviation @ 10-4 BER
21
OSNR Requirement for 10-3 BER
4
5
6
7
8
9
0 500 1000 1500 2000
Distance (km)
OS
NR
(d
B) 18G
9G
6G
15G
• OSNR requirement is <7dB @1200km• Getting high OSNR at short distances is easy.
22
OSNR Requirement for 10-4 BER
7
8
9
10
11
12
0 500 1000 1500 2000
Distance (km)
OS
NR
(d
B) 18G
9G
6G
15G
• OSNR requirement is <11dB @2000km and <9dB for 1200km
23
Effect of launch power on 18 GHz Channel
1.00E-05
1.00E-04
1.00E-03
5 6 7 8 9 10 11 12 13 14 15
OSNR (dB)
BE
R
-4.5dBm
-3.5dBm
-2.5dBm
• Penalty increase is <1dB from -4.5dBm to -3.5dBm• Optimum launch power is ~-3.5dBm
24
Effect of launch power on 6 GHz Channel
1.00E-06
1.00E-05
1.00E-04
1.00E-03
5 6 7 8 9 10 11 12 13 14 15
OSNR (dB)
BE
R
-4.5dBm
-3.5dBm
-2.5dBm
• Penalty increase is <1dB from -4.5dBm to -3.5dBm
25
Spectrum for LP Variation
-4.5 dBm LP -2.5 dBm LP
19.3dB 17.2dB
• After 2000km but spectrum is filtered after 1000km with a 40GHz Demux.
• Uneven channel spacing helps nonlinearity performance
26
RF Spectrum before Optical Modulator
All 4 channels
18 GHz Ch
15 GHz Ch
10dB/div
2dB/div
27
Effect of LPFing on Spectrum
• LPF is a 1Ghz ~4th order Bessel filter
28
Conclusion
10Gb/sec 2000km no dispersion compensation transmission demonstrated
Flat group delay large bandwidth devices are designed
Our microwave techniques enable high spectral efficiency, low cost, high performance optical systems