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 VVV 0V0 0E0-E Data EXOR Data Encoder Out LPF In LPF Out Modulator Out At receiver Differential Encoder Low pass filter Modulator biased at null

5 Low Pass Filtering 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 Quadrature Hybrid Laser Dual Arm Modulator Notch Filter 0˚90˚ We only use the subcarrier channels at the receiver

9 Transmitter 15GHz 18GHz 6GHz 9GHz LaserModNotch FilterAmplifier 90° Hybrid Σ Σ 18GHz LO Absorptive LPF 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

12 Up Converter Center Block

13 Link 6 or km spans Demux 2x1 EDFA ASE Source VOA OSA

14 Receiver Decision threshold bias 1x2 FP Tunable 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 Confidential / ©2005 OpVista, Inc. 0 km 600 km1200 km 2000 km

17 9 GHz Channels Performance 600 km1200 km 2000 km 0 km

18 6 GHz Channel Performance 600 km1200 km 2000 km 0 km

19 15 GHz Channel 0 km 600 km1200 km 2000 km

km Performance <1dB OSNR BER

21 OSNR Requirement for BER OSNR requirement is Getting high OSNR at short distances is easy.

22 OSNR Requirement for BER OSNR requirement is and <9dB for 1200km

23 Effect of launch power on 18 GHz Channel 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 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 ~4 th 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