Theoretical and Experimental Results on Transmission Penalty Due to Fiber Parametric Gain in Normal Dispersion A. Carena, V. Curri, R. Gaudino, P. Poggiolini, S.Benedetto F. Bentivoglio, M. Frascolla, C. Rocca
Communications Group - Politecnico di Torino Pirelli Cables Systems Conclusions. Outline Introduction. The origin of Parametric Gain (PG) and its system impact. Description of the Transfer Matrix analytical tool developed both dispersion regions. for Sideband Instability, an eect related to Parametric Gain in presence of periodical links. the Experimental measurements on a recirculating loop. Comparison between experimental, theoretical and simulated results. 2
Communications Group - Politecnico di Torino Pirelli Cables Systems Introduction PG is caused by the interaction of ber nonlinearities with dispersion. PG induces a transfer of optical power from the signal to the noise, in both dispersion regions. ASE PG eects dispersion region ) Noise Enhancement Anomalous Modulation Instability Normal dispersion region ) Noise Enhancement Periodical structures are aected by Sideband Instability too. 3
Communications Group - Politecnico di Torino Pirelli Cables Systems PG linearized equation @a = 1 2 2 @z @ 2 a Parametric Gain (I) @T 2, P 0e (,2z) (a + a ) PG characteristics depend on: L Fiber length D Dispersion parameter Nonlinear parameter P0 Pump power Attenuation parameter 4
Communications Group - Politecnico di Torino Pirelli Cables Systems pp. 535-537, Apr. 1997. Parametric Gain (II) G(z; ) = 2 G pp(z; ) G pq (z; ) 4 ) G qq (z; ) Gqp(z; Reference Carena,V. Curri, R. Gaudino, P. Poggiolini New theoretical result on ber Parametric A. Gain and its eects on ASE noise, IEEE Photonics Technology Letters, vol. 9, n. 4, 3 5 5
Communications Group - Politecnico di Torino Pirelli Cables Systems Sideband Instability 6
Communications Group - Politecnico di Torino Pirelli Cables Systems OPTSIM - System Simulator Time-domain simulator. It is based on a split-step algorithm. A dual polarization ber model is considered to include all related phenomena. polarization It takes into account attenuation, dispersion, birefringence PMD. and Non-linear Kerr eect is considered, too. Joint linear-nonlinear eects are accurately evaluated. 7
Parameters: CW power: 0 dbm, Fiber loss: = 0.22 db/km, Fiber nonlinearity: = 2 W,1 km,1. Pirelli Cables Systems Communications Group - Politecnico di Torino Amplied Link, DS Fiber, L=3,000 km DSF D = -/+ 1.6 ps/nm/km L = 50 km TX RX EDFA # 1 NF = 5 db EDFA # 2 NF = 5 db EDFA # N NF = 5 db 8
Pirelli Cables Systems Communications Group - Politecnico di Torino Noise gain after 3,000 km, D=+1.6 ps/nm/km 10 Gain [db] 8 6 4 2 0-2 -4 In-Phase Quadrature 0 10 20 30 40 50 f - f 0 [GHz] 1: Simulated (dashed) and analytical (solid) in-phase Figure quadrature ASE noise gain spectra. Anomalous dispersion. and 9
Pirelli Cables Systems Communications Group - Politecnico di Torino Noise gain after 3,000 km, D=-1.6 ps/nm/km 10 Gain [db] 8 6 4 2 0-2 -4 Quadrature In-Phase 0 10 20 30 40 50 f - f 0 [GHz] 2: Simulated (dashed) and analytical (solid) in-phase Figure quadrature ASE noise gain spectra. Normal dispersion. and 10
Communications Group - Politecnico di Torino Pirelli Cables Systems Experimental setup s = 1539 nm B R = 2.5 Gbit/s 0 = 1565 nm D = -0.48 ps/nm/km = 0.224 db/km EDFA output power P0= +9 dbm 11
Pirelli Cables Systems Communications Group - Politecnico di Torino Power Spectrum [db] 45 40 35 30 25 20 N = 12 15 10 N = 8 5 N = 0 0-5 -1.0-0.8-0.6-0.4-0.2 0.0 0.2 0.4 0.6 0.8 1.0 Wavelength [nm] Experimental and simulated results: spectra 12
For transmitted \1"s PG eects on ASE noise are evaluated. analytically For transmitted \0"s linear propagation of ASE noise is assumed. Distorsion of the signal is neglected. Pirelli Cables Systems Communications Group - Politecnico di Torino Filter Photodetector Electric Filter Analitycal Evaluation of Q-parameter E(t) E f (t) 2 E f (t) V(t) = 1, 0 Q 1 + 0 Fabry-Perot filter Bw = 0.25 nm Ideal device Bessel filter Bw = 0.8 Rb GHz 13
Pirelli Cables Systems Communications Group - Politecnico di Torino Q parameter comparison 22 Ideal Q [db] 20 18 Measure Linear 16 Simulation 14 Theoretical 8 9 10 11 12 Loop Number 14
Communications Group - Politecnico di Torino Pirelli Cables Systems Conclusions Parametric Gain occurs in normal dispersion as well. In long-haul systems PG can be one of the most important phenomena. limiting PG characteristics are determined by signal intensity and dispersion. ber A new analytical tool for the evaluation of the impact of PG been derived. has Good agreement between experiments, simulation and has been obtained. theory 15