1. UPC-GCO
UPC-
GCO
Homodyne OLT-ONU design for
access optical networks
Universitat Politècnica de Catalunya
Advisor:
Advisor: Josep Prat Student:
Student: Josep Mª Fàbrega
Mª
Universitat Politècnica de Catalunya (UPC)
Dept. of Signal Theory and Communications (TSC)
Optical Communications Group (GCO)
www.tsc.upc.edu/gco

2. UPC Thesis proposal
GCO
Introduction
∙ Homodyne systems in access networks
State of the art
∙ What we have done
Thesis index
Work plan
Publications and dissemination

3. UPC Introduction
GCO
Migration from TDM/WDM to pure WDM [1]
Ultra-dense WDM PONs
∙ Multiple low capacity channels
E.g. 1 Gbps
OL
3 GHz
...........................
λ
More than 1500 ch. at C band

4. UPC Introduction
GCO
∙ IM-DD systems limited
Sensitivity
Optical filters selectivity
∙ Coherent systems
Heterodyne Optical
I p(t)
-
Input
– Image frequency problems +
Homodyne
Local
– Phase locking problems [2] Laser

5. UPC Network Schemes
GCO
2) with MUX & splitters[D8]:
1) with splitters CPE CPE
CPE
nd
DM ba
CPE
λ1 D-W
CPE CPE
CPE
K CPEs
CPE λ1 .. λN D-WDM bands
OLT
CO
CPE λ CPE
CPE D-
N
W Nx PONs
DM
CPE
CO CPE ba
nd
D-WDM CPE
CPE MUX
CPE
(RN 1) CPE
D-WDM band
CPE
CPE power
splitter CPE
(RN 2)
3) SARDANA [3]: K UD-WDM channels
down-signals
1 wavelength 1 user
CO
RN16 RN1
up-signals
Long reach (>100 km)
Add/Drop
Pump 100 km Ring
WDM WDM
Pump
Pump
Large number of users
λ i2 λ i1
(>1500 @ 1 Gbps)
rEDFs rEDFs ONU
ON
ONU
ON
1:32 1:32
RN i
No TDM bandwidth
ONU
ON
ONU
ON
RN x up
sharing
K UD-WDM channels

6. UPC OLT and ONU philosophy
GCO
OLT Tx/Rx and ONU are intended to
have the same architectures
PSK main modulation format for both
upstream and downstream
Other modulation formats can be
envisaged (PSK/IM, QAM/QAM)
Main impairments
∙ Laser phase noise
∙ Polarization fluctuations

7. UPC Thesis proposal
GCO
Introduction
∙ Homodyne systems in access networks
State of the art
∙ What we have done
Thesis index
Work plan
Publications and dissemination

8. UPC ONU Schemes
GCO
Optical Phase-Locked Loop
Phase/Polarization diversity
Phase/Polarization scrambling

9. UPC ONU Schemes: oPLL ONU
GCO
-
Optical In/Out Data out
PM or IM +
Modulator
Hold-In Margin for several loops
9
8
7
Hold-In margin (GHz)
Phase
6
Local
5
control and
Laser
4
recovery
3
2
Linewidth tolerance for several loops
1
0
30
Heterodyne Balanced Costas SC-PLL
Phase error deviation (degrees)
27 Balanced Costas
Several oPLL architectures to study 24
Costas Loop [4]
∙ 21
Decision Driven [5]
∙
18 Heterodyne
Balanced [6]
∙
15
Lock-In amplifier (heterodyne) [7]
∙
12
SubCarrier Modulated [8]
∙
BER-floor 9
6
10-9 BER
∙ 10º SCM
SubCarrier Modulated
10-3 BER
∙ 28º Lock-In 3
Hold-In margin 0
0 1 2 3 4 5 6 7
∙ SCM: 7.68 GHz
Total laser linewidth (MHz)
∙ Lock-In: 896 MHz

10. UPC ONU Schemes: 90º Hybrid ONU
GCO
Low cost if implemented with polymeric waveguides
Polarization insensitive when combined with PBS
Possible use of advanced and non-linear signal
processing techniques to improve data detection [9]
Total laser linewidth per symbol rate ratio tolerance
up to 3.2% using linear phase estimation [10]
90º Hybrid
I
Optical In /Out Data Out
I and Q
ADC
Post-processing
PM or AM
Q
Modulator
Data
Local Wavelength control
laser

11. UPC ONU schemes: Phase Scrambling ONU
GCO
Optical In/Out Data out
- I and Q
Post-processing
PM or IM +
Modulator
Phase
Scrambler
Sensitivity penalty vs channel spacing
CLK
3,5
Recovery
3
Sensitivity penalty (dB )
2,5
2
1,5
1
Local
0,5
0
Laser
I Q I Q
0 1 2 3 4 5 6 7
Channel spacing (GHz)
t
t0 t0+T/2 t0+T t0+3T/2 t0+2T
Sensitivity measurements
Very simple optics
-2
Total laser linewidth per symbol rate ratio
-3 Downstream
tolerance up to 18%
-4 Upstream
<3GHz ch. spacing at 1 Gbps (<1.5 dB penalty)
-5
log(BER)
-38.7 dBm sensitivity @ 10-9 BER
-6
~3 dB penalty due to phase scrambling
-7
Idea and first experiments [D2, D4, D9, D12]
-8
Digital Signal Processing version based in
-9
Fuzzy logic data estimation [D3]
-10
Version with both, polarization and phase
-48 -46 -44 -42 -40 -38 -36
scrambling
Input power (dBm)

12. UPC ONU schemes: Phase Scrambling ONU
GCO
Data out
Optical In /Out - I and Q
Post-processing
PM or IM +
Modulator
CLK
BER-floor vs laser linewidth
-1
Recovery
γ =1
-2
Local
log(BER)
-3
Laser
Square wave
γ=
-4
-5
1 2 3 4 5 6 7 8 9 10
Linewidth/bitrate (%)
127º
Sensitivity results
0
-1
Low cost homodyne receiver
-2
Very simple optics
-3
log(BER)
-4
Total laser linewidth per symbol rate ratio
γ =1
tolerance up to 3.2%
-5
-6
~3 dB penalty due to phase scrambling
Square wave
-7
Sensitivity expected -36 dBm @ 10-9 BER
-8
γ= Idea and first results [D4]
-9
-10
-43 -42 -41 -40 -39 -38 -37 -36 -35
Received Power (dBm)

13. UPC OLT Scheme
GCO
Transceivers scheme same as ONU
Polarization scrambling can be done at OLT
Bidirectional
K Tx/Rx Polarization
Scrambler
Tx/Rx
At the OLT
∙ Phase scrambling is done at
I
Q Q I Q Q I I
Tx/Rx
∙ Polarization scrambling is done
H H
V V H V H V
after coupling transceiver
outputs
t t+T t+2T
At the ONU
∙ Only phase scrambling

14. UPC Thesis proposal
GCO
Introduction
∙ Homodyne systems in access networks
State of the art
∙ What we have done
Thesis index
Work plan
Publications and dissemination

15. UPC Thesis index
GCO
Executive summary
Introduction
∙ Background
∙ Scope of work
∙ Document organization
Network topologies
∙ Tree topologies
∙ Ring topologies
OLT and ONU architectures
∙ Lock-In amplifier oPLL architecture
∙ Phase / polarization diversity architectures
i. Full phase / polarization diversity
– 1. K-L phase estimation
– 2. Fuzzy data estimation
ii. Time switched phase / polarization diversity
– 1. Differential detection
– 2. K-L phase estimation
– 3. Fuzzy data estimation
c. Performance summary
Cost analysis and comparison
Conclusions and future lines
Publications
References
Appendixes

16. UPC Thesis proposal
GCO
Introduction
∙ Homodyne systems in access networks
State of the art
∙ What we have done
Thesis index
Work plan
Publications and dissemination

17. UPC Work Plan
GCO
Research period
∙ Reach a complete knoweldege on:
Signal processing
Network topologies
Tx/Rx architectures
∙ Propose improvements/original techniques
Evaluation of the architectures
∙ Simulations
∙ Proof-of-concept experiments.
Prototype implementation
∙ Prototype assembled in some PON testbeds
∙ Arrange stays outside UPC (perform late
experiments)
Redaction of the thesis

18. UPC Work Plan
GCO
jan feb mar apr may jun jul aug sep oct nov dec
2006
2007
2008
2009
Research period (19 months)
Evaluation of the architectures (12 months)
Prototype implementation (6 months)
Redaction of the thesis (6 months)

19. UPC Thesis proposal
GCO
Introduction
∙ Homodyne systems in access networks
State of the art
∙ What we have done
Thesis index
Work plan
Publications and dissemination

20. UPC Publications and dissemination
GCO
2 patents
3 journal articles
11 conference contributions (6 ECOC, 1 OFC, and others)
PATENTS
[D1] Josep Prat, Josep M. Fàbrega “Receptor homodino para comunicaciones ópticas con procesado a posteriori,” P-200700041, priority date:
29/12/2006
[D2] Josep Prat, Josep M. Fàbrega, Joan M. Gené “Receptor coherente homodino para comunicaciones ópticas con demodulación diferencial,” P-
200500998, priority date: 21/04/2005
JOURNAL ARTICLES
J. M. Fàbrega, J. Prat, “Experimental Investigation of Channel Crosstalk in a Time-Switched Phase Diversity Optical Homodyne Receiver,” OSA
[D3]
Optics Letters, vol. 34, No. 4, February 2009
J. M. Fàbrega, J. Prat, “Homodyne receiver prototype with time-switching phase diversity and feedforward analog processing,” OSA Optics
[D4]
Letters, vol. 32, No. 5, March 2007
J. M. Fàbrega, J. Prat, “Fuzzy Logic Data Estimation Based PSK Receiver with Time-switched Phase Diversity”, IEE Electronics Letters, vol. 42,
[D5]
no. 16, August 2006
CONFERENCES
[D6] J. M. Fabrega, E. T. López, J. A. Lázaro, M. Zuhdi, J. Prat, “Demonstration of a full duplex PON featuring 2.5 Gbps sub carrier multiplexing
downstream and 1.25 Gbps upstream with colourless ONU and simple optics” European Conference on Optical Communications ECOC'08,
Brussels, Belgium, September 2008.
[D7] J. M. Fabrega, L. Vilabru, J. Prat, “Experimental Demonstration of Heterodyne Phase-locked loop for Optical Homodyne PSK Receivers in
PONs” International Conference on Transparent Optical Networks ICTON’08, Athens, Greece, June 2008.
J. M. Fabrega, J. Prat, “Simple Low-Cost Homodyne Receiver,” European Conference on Optical Communications ECOC'07, Berlin, Germany,
[D8]
September 2007.
[D9] J. Prat, J. A. Lázaro, J. M. Fabrega, V. Polo, C. Bock, C. Arellano, M. Omella, “Next Generation Architectures for Optical Access and Enabling
Technologies,” 5ª Reunión española de Optoelectrónica OPTOEL’07, Bilbao, Juliol de 2007
[D10] J. M. Fabrega, J. Prat, “Channel Crosstalk in ultra-dense WDM PON using Time-Switched Phase Diversity Optical Homodyne Reception,”
International Conference on Transparent Optical Networks ICTON’07, Rome, Italy, July 2007.
J. M. Fabrega, J. Prat, “Homodyne PSK Receiver with Electronic-Driven Phase Diversity and Fuzzy Logic Data Estimation”, European
[D11]
Conference on Optical Communications ECOC'06, Cannes, France, September 2006.
[D12] C. Bock, J. M. Fabrega, J. Prat, “Ultra-Dense WDM PON based on Homodyne Detection and Local Oscillator Reuse for Upstream
Transmission”, European Conference on Optical Communications ECOC'06, Cannes, France, September 2006.
J. M. Fabrega, J. Prat, “Homodyne Receiver Implementation with Diversity Switching and Analogue Processing”, European Conference on
[D13]
Optical Communications ECOC'06, Cannes, France, September 2006.
[D14] J. M. Fabrega, J. Prat, “Optimization of Heterodyne Optical Phase-Locked Loops: Loop Delay Impact and Transient Response Performances”,
International Conference on Telecommunications ICT’06, Funchal (Madeira), Portugal, May 2006.
J. M. Fabrega, J. Prat, “New Intradyne Receiver with Electronic-Driven Phase and Polarization Diversity”, Optical Fiber Communication
[D15]
OFC/NFOEC’06, paper JThB45, Anaheim (CA), USA, March 2006.
J. Prat, J.M. Fabrega, “New Homodyne Receiver with Electronic I&Q Differential Demodulation”, European Conference on Optical
[D16]
Communications ECOC'05, paper We4.P.104, Glasgow, UK, September 2005.

21. UPC References
GCO
[1] C.-H. Lee, W. V. Sorin and B. Y. Kim, “Fiber to the Home Using a PON Infrastructure”,
Journal of Lightwave Technology, vol. LT-24, no. 12, Dec. 2006, pp. 4568-4583
[2] L. Kazovsky, G. Kalogerakis and W.-T. Shaw, “Homodyne Phase-Shift-Keying
Systems: Past Chalenges and Future Opportunities,” Journal of Lightwave Technology,
vol. LT-24, no. 12, Dec. 2006, pp. 4876-4884
[3] J. A. Lázaro et al. “Scalable Extended Reach PON,” in Proc. OFC/NFOEC 2008,
OThL2.
[4] H.K.Philipp, A.L.Scholtz, E.Bonek, W.R.Leeb, “Costas Loop Experiments for a 10.6µm
Communications Receiver”, IEEE Transactions on Communications, vol. COM-31, no.
8, Aug. 1983.
[5] L.G. Kazovsky, “Decision-Driven Phase-Locked Loop for optical homodyne receivers:
performance analysis and laser linewidth requirements” Journal of Lightwave
Technology, vol LT-3, no. 6, Dec. 1985
[6] L.G. Kazovsky, “Balanced PLL for optical homodyne receivers: performance analysis,
design considerations, and laser linewidth requirements,” Journal of Lightwave
Technology, vol LT-4, no. 2, Feb. 1986
[7] K.H. Kudielka and W. Klaus, “Optical homodyne PSK receiver: Phase synchronization
by maximizing baseband signal power,” in Proc. LEOS 1999, TuU2.
[8] S. Camatel et al., “Optical phase-locked loop for coherent detection optical receiver,”
Electronics Letters, vol. 40, no. 6, Mar. 2004
[9] R. Noé, “Phase noise-tolerant synchronous QPSK/BPSK baseband-type intradyne
receiver concept with feedforward carrier recovery,” Lightwave Technology, Journal of,
2005, 23, 802-808 (2005)
[10] M. G. Taylor, “Accurate digital phase estimation process for coherent detection using a
parallel digital processor” 31st European Conference on Optical Communication, 2005.
ECOC 2005. Volume 2, 25-29 Sept. 2005 Page(s):263 - 264 vol.2

22. UPC-GCO
UPC-
GThanksO
C !!
Universitat Politècnica de Catalunya
Mª
Josep Mª Fàbrega
jmfabrega@tsc.upc.edu
Universitat Politècnica de Catalunya (UPC)
Dept. of Signal Theory and Communications (TSC)
Optical Communications Group (GCO)
www.tsc.upc.edu/gco