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