TX X s 10 GBIT/S 2-PSK TRANSMISSION AND HOMODYNE …
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10 12 14 16 18 20 10 12 14 16 18 20 OSNR [dB] Q [dB] 10 GBIT/S 2-PSK TRANSMISSION AND HOMODYNE COHERENT DETECTION USING COMMERCIAL OPTICAL COMPONENTS Stefano Camatel, Valter Ferrero, Roberto Gaudino, Pierluigi Poggiolini - Politecnico di Torino Paolo Bravetti, Giuliano Coli - Corning-OTI (now Avanex) A.P.S.Khanna -Agilent Technologies ➢Coherent detection: potential field of application: ▪ Multilevel optical phase modulation (N-PSK) ▪ Dispersion compensation in the electrical domain ▪ Ultra-dense WDM ▪ Fastly reconfigurable optical networks ▪ Optical sensor, microwave photonics, etc. ➢Targets of this work: ▪ We introduce a novel technique to implement an optical homodyne PLL using only off-the-shelf optical components ▪ We demonstrate its feasibility on a 10 Gbit/s PSK experiment • We show that the RX sensitivity is significantly better than conventional IM-DD 10Gbps PSK TX 3dB Coupler ASE Source Optical Filter 10Gbps RX Optical VCO Loop Filter 3dB Coupler OSA LO VCO f f ± c v() t TX f Polarization Controller SC-OPLL System schematic Electrical VCO External Cavity Laser B Optical Amplitude Modulator c v() t LO VCO f f ± LO f VCO f Power Driver 3dB Coupler V b R 1 R 2 C R 1 Loop Filter Optical VCO INPUT OUTPUT Sub Carrier Optical PLL (SC-OPLL) LO f LO VCO f f - LO VCO f f + Two main Sub Carriers at frequency f LO f VCO are generated. We are able to tune both by simply changing the voltage applied to the electrical VCO, thus implementing an Optical VCO. f LO is set in order to obtain f LO -f VCO equal to the received signal frequency f TX . At photodiode output, the signal carried by the transmitter is translated to base-band. In principle, due to beating with the other SCs, copies of this signal appears also around frequencies fVCO and 2fVCO, but they are filtered out by the electrical receiver filter. modulated PSK signal Photodiode Input f LO -f VCO f LO f LO +f VCO electrical low-pass filter DC f VCO 2f VCO Electrical VCO External Cavity Laser B Optical Amplitude Modulator c v() t LO VCO f f ± LO f VCO f Power Driver OPTICAL OUTPUT ELECTRIC INPUT The amplitude modulator is a high bandwidth Corning-OTI LiNbO3 Mach-Zehnder (MZ) and is biased at a null of its transfer function, a sinusoidal carrier-suppressed modulation is obtained. The electrical VCO is a low jitter silicon- bipolar based 20 GHz VCO from Agilent Technologies. Laser A Phase Modulator 10 Gbps Pattern Generator TX f Power Driver The transmitter is based on a Corning-OTI LiNbO 3 10Gbit/s phase modulator, driven by an NRZ signal. The modulation voltage has been set to a slightly lower value than the modulator V π voltage. The SC-OPLL locks the residual carrier. “1” “0” Residual carrier 10Gbps 2-PSK Transmitter The Sub-Carrier OPLL (SC-OPLL) is our novel OPLL setup. It is the key element of the proposed coherent system. Experimental Results PSK IMDD Optical VCO Output signal Received signal Optical VCO SC-OPLL: Spectrums Photodiode Output 10Gbps PSK System OSNR=14 dB Measured Q = 15.6 dB 10Gbps IM-DD System OSNR=18 dB Measured Q = 15.8 dB Conclusions ➢ All the SC-OPLL components are commercially available today ➢ We demonstrated its feasibility on a 10 Gbit/s PSK experiment ▪ RX sensitivity is 4 dB better than conventional IM-DD ➢ For any further information, please contact us ▪ Stefano Camatel – [email protected] ▪ Valter Ferrero – [email protected] ▪ Roberto Gaudino – [email protected] www.optcom.polito.it Acknowledgements ➢ This project was partially funded by CISCO, University Research Program (URP)
Transcript of TX X s 10 GBIT/S 2-PSK TRANSMISSION AND HOMODYNE …
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OSNR [dB]
Q [
dB
]10 GBIT/S 2-PSK TRANSMISSION AND HOMODYNE COHERENT
DETECTION USING COMMERCIAL OPTICAL COMPONENTS
Stefano Camatel, Valter Ferrero, Roberto Gaudino, Pierluigi Poggiolini - Politecnico di Torino
Paolo Bravetti, Giuliano Coli - Corning-OTI (now Avanex)
A.P.S.Khanna - Agilent Technologies
➢Coherent detection: potential field of application:
▪Multilevel optical phase modulation (N-PSK)
▪Dispersion compensation in the electrical domain
▪Ultra-dense WDM
▪ Fastly reconfigurable optical networks
▪Optical sensor, microwave photonics, etc.
➢Targets of this work:
▪ We introduce a novel technique to implement an optical
homodyne PLL using only off-the-shelf optical components
▪ We demonstrate its feasibility on a 10 Gbit/s PSK experiment
• We show that the RX sensitivity is significantly better than
conventional IM-DD
10GbpsPSK TX 3dB
Coupler
ASESource
OpticalFilter
10GbpsRX
OpticalVCO
LoopFilter
3dBCoupler
OSA
LO VCOf f±
cv ( )t
TXf PolarizationController
SC-OPLL
System schematic
ElectricalVCO
External CavityLaser B
OpticalAmplitudeModulator
cv ( )t
LO VCOf f±
LOf
VCOf
PowerDriver
3dBCoupler
Vb
R1
R2C
R1 LoopFilter
OpticalVCO
INPUT
OUTPUT
Sub Carrier Optical PLL (SC-OPLL)
LOfLO VCOf f-LO VCOf f+
Two main Sub Carriers at frequency fLOfVCO are
generated. We are able to tune both by simply
changing the voltage applied to the electrical VCO,
thus implementing an Optical VCO.
fLO is set in order to obtain fLO-fVCO equal to the
received signal frequency fTX.
At photodiode output, the signal
carried by the transmitter is
translated to base-band. In
principle, due to beating with the
other SCs, copies of this signal
appears also around frequencies
fVCO and 2fVCO, but they are
filtered out by the electrical
receiver filter.
modulated
PSK signal
Photodiode Input
fLO-fVCO fLO fLO+fVCO
electrical
low-pass filter
DC fVCO 2fVCO
ElectricalVCO
External CavityLaser B
OpticalAmplitudeModulator
cv ( )t
LO VCOf f±LOf
VCOf
PowerDriver
OPTICALOUTPUT
ELECTRICINPUT
The amplitude modulator is a high bandwidth
Corning-OTI LiNbO3 Mach-Zehnder (MZ)
and is biased at a null of its transfer function,
a sinusoidal carrier-suppressed modulation is
obtained.
The electrical VCO is a low jitter silicon-
bipolar based 20 GHz VCO from Agilent
Technologies.
Laser APhase
Modulator
10 GbpsPattern
Generator
TXf
PowerDriver
The transmitter is based on a Corning-OTI LiNbO3 10Gbit/s phase
modulator, driven by an NRZ signal. The modulation voltage has
been set to a slightly lower value than the modulator Vπ voltage.
The SC-OPLL locks the residual carrier.
“1”
“0”
Residual carrier
10Gbps 2-PSK Transmitter
The Sub-Carrier OPLL (SC-OPLL) is our novel OPLL setup.
It is the key element of the proposed coherent system.
Experimental Results
PSKIMDD
Optical VCO Output signal
Received signal
Optical VCO
SC-OPLL: Spectrums
Photodiode Output
10Gbps PSK System
OSNR=14 dB
Measured Q = 15.6 dB
10Gbps IM-DD System
OSNR=18 dB
Measured Q = 15.8 dB
Conclusions
➢All the SC-OPLL components are commercially available today
➢We demonstrated its feasibility on a 10 Gbit/s PSK experiment
▪ RX sensitivity is 4 dB better than conventional IM-DD
➢For any further information, please contact us
▪ Stefano Camatel – [email protected]
▪ Valter Ferrero – [email protected]
▪ Roberto Gaudino – [email protected]
www.optcom.polito.it
Acknowledgements
➢This project was partially funded by CISCO, University Research
Program (URP)
