Effect of optical amplifier noise on laser linewidth requirements in long haul optical fiber communication systems with Costas PLL receivers

The impact of optical amplifier noise is analyzed in investigating the performance of optical long-haul PSK homodyne communication systems with Costas phase locked loop (PLL) receivers. The laser linewidth requirement for an optically amplified system becomes relaxed in comparison with the system with no optical amplifier, owing to the fact that the effect of incomplete phase tracking becomes less important as a larger signal power is demanded to maintain a fixed bit-error rate. Also, it is found that the power splitting ratio regarding the power distributions for the I-arm and the Q-arm of a Costas loop can vary in a wide range without having much influence on the performance of an optically amplified system. As a matter of fact, the power penalty induced by incomplete phase tracking for a system with a large number of cascaded optical amplifiers is mainly due to the finite phase error and not due to the power splitting ratio, and this may fail a previously-reported method for finding the required laser linewidth by assigning a certain amount of power penalty that is due to the power splitting ratio.

[1]  A.E. Willner.  SNR analysis of crosstalk and filtering effects in an amplified multichannel direct-detection dense-WDM system , 1992, IEEE Photonics Technology Letters.

[2]  L. Kazovsky.  Decision-driven phase-locked loop for optical homodyne receivers: Performance analysis and laser linewidth requirements , 1985, IEEE Transactions on Electron Devices.

[3]  Yu Wang,et al.  Sensitivity Analysis and Performance Optimization of an Optical Costas Phase-Locked Loop , 1987 .

[4]  W. Michie,et al.  The performance of optical phase-locked loops in the presence of nonnegligible loop propagation delay , 1987 .

[5]  Leonid G. Kazovsky,et al.  Balanced phase-locked loops for optical homodyne receivers: Performance analysis, design considerations, and laser linewidth requirements , 1986 .

[6]  T. Okoshi,et al.  Heterodyne and Coherent Optical Fiber Communications: Recent Progress , 1982 .

[7]  Leonid G. Kazovsky,et al.  Performance analysis and laser linewidth requirements for optical PSK heterodyne communications systems , 1986 .

[8]  Peter Atkinson,et al.  Phase-Locked and Frequency Feedback Systems , 1979, IEEE Transactions on Systems, Man, and Cybernetics.

[9]  L. D. Tzeng,et al.  2.488 Gb/s-318 km repeaterless transmission using erbium-doped fiber amplifiers in a direct-detection system , 1992, IEEE Photonics Technology Letters.

[10]  W. R. Leeb,et al.  Optical 90 degrees hybrid Costas-type receivers , 1990 .

[11]  Takeshi Ito,et al.  An over 2200-km coherent transmission experiment at 2.5 Gb/s using erbium-doped-fiber in-line amplifiers , 1991 .

[12]  Compensation for chromatic dispersion and nonlinear effect in high dispersive coherent optical repeater transmission system , 1993 .

[13]  T. Hodgkinson.  Costas loop analysis for coherent optical receivers , 1986 .

[14]  N. Edagawa,et al.  Long-haul coherent optical fiber communication systems using optical amplifiers , 1991 .

[15]  Chau-Chiun Huang,et al.  Optimum phase deviations between mark-and space-state bits in long-haul coherent communication systems with balanced PLL receivers , 1995 .

[16]  Katherine L. Hall,et al.  Balanced dual-detector receiver for optical heterodyne communication at Gbit/s rates , 1986 .

[17]  High sensitivity 10 Gbit/s optical receiver using two cascaded EDFA preamplifiers , 1991 .