1. A GENERALIZED FIBER FIGURE OF MERIT INCLUDING RAMAN AMPLIFICATION
V. Curri(1), A. Carena(1), G. Bosco(1), P. Poggiolini(1),
F. Forghieri(2)
(1)DET, Politecnico di Torino, Torino, Italy.
(2)Cisco Photonics Italy srl, Monza, Italy.
FOTONICA Paper C2.5

2. Motivation and outline
Which is the fiber type giving the maximum reach in uncompensated links?
What is the merit of Raman amplification?
FoM definition based on max reach for EDFA-based links
Use of aproximated GN-model to define a practical FoM expression with clear dependence on fiber parameters
Validation using experimental and simulative published results
Extension to hybrid Raman/EDFA amplification (HFA)
Validation for HFAs
FOTONICA Paper C2.5

3. System scenario Rx Rx + X Ns EDFA X Ns G D,a,g AI Ao WDM Tx Ls G=As F
FOTONICA Paper C2.5

4. Nonlinear OSNR Nonlinear OSNR
Given the modulation format and Tx/Rx setups
Target performance means target OSNRNL
Reach vs. Pch
NLI power
FOTONICA Paper C2.5

5. Max reach given the target performanceNs
Max reach
Pch
Optimal power
Max reach given the target performance
FOTONICA Paper C2.5

6. Figure of Merit GN-model
Max reach is a quality parameter usable as FoM…
Removing fiber independent parameters…
Dependence on system parameters is in h
NOTE: exactly the same FoM expression can be obtained maximizing the system margin given the distance (minimization of BER)
GN-model
FOTONICA Paper C2.5

7. FoM based on Max Reach (or min BER)
FoM expression
GN model
Large Nch
Rs = 20 → 40 [Gbaud]
Df /Rs < 1.3
adB = 0.15 → 0.22 [dB/km]
D = 4 → 24 [ps/nm/km]
We can consider this term as a constant with a max reach error
lower than ½ dB
EDFA
In order to compare different fibers differential FoM is used, given a reference scenario
FoM based on Max Reach (or min BER)
FOTONICA Paper C2.5

8. Experimental validation
100G PM-QPSK
NyWDM
10 channels
BER = 10-3
Maximum DFoM
experimental vs. theory inaccuracy: 0.4 dB
100G PM-QPSK
Df = 50 GHz
11 channels
BER = 3.8∙10-3
100G PM-QPSK
Df = 50 GHz
80 channels
Q2 ≈ 9.8 dB
FOTONICA Paper C2.5

9. Simulative validation
PSCF
SSMF
NZDSF
4 mod formats
Optical NyWDM
3 fibers
Rs = 32 Gbaud
Df = 32→50 GHz
9 channels
216 symbols
Error counting
BER = 10-3
Maximum
sim vs. theo DFoM inaccuracy:
0.5 dB
FOTONICA Paper C2.5

10. Application to HFA-based setups
Polarization
diversity Rx
X Ns
EDFA Ls
Nyquist
WDM Tx
D,a,g
GEDFA
FEDFA
Ppump
LMS
DSP
FOTONICA Paper C2.5

11. FoM and HFA: validation setup
Simulation of NyWDM 200G PM-16QAM
19 channels
Minimum BER analysis
10 spans, Ls = 100 km
3 amplification schemes
EDFA only
Ppump = 500 mW
GRA = 16 dB
Four typical fiber types
Fiber
adB
[dB/km] b2
[ps2/km] D
[ps/nm/km] g
[1/W/km]
NZDSF
0.22
-4.8
3.8
1.5
SSMF
-21.3
16.7
1.1
ULLF
0.16
PSCF
-26.1
20.6
0.8
FOTONICA Paper C2.5

12. FoM and HFA: validation results
EDFA only
Ppump = 500 mW
GRA = 16 dB
Fiber
DFoM [dB]
EDFA only
Ppump = 500 mW
GRA = 16 dB
Sim
Theory
NZDSF
-2.7
-3.0
-0.3
-0.8
+0.1
-0.4
SSMF
0.0
+1.9
+1.8
+2.8
+2.6
ULLF
+3.2
+3.5
+5.6
+5.2
+5.7
+5.3
PSCF
+4.3
+4.7
+6.1
+6.6
+6.5
Maximum DFoM
simulation vs. theory
inaccuracy: 0.5 dB
FOTONICA Paper C2.5

13. Comments and conclusions
A simple expression of fiber FoM was proposed
It gives clear dependence on fiber parameters
It has been sucessfully validated using published results
Extension to systems using HFA was proposed and validated by simulation
FOTONICA Paper C2.5

14. This work was supported by CISCO Systems within a SRA contract
Acknoledgemets
This work was supported by CISCO Systems within a SRA contract
The simulator OptSimTM was supplied by Synopsys Inc.
FOTONICA Paper C2.5