Cross-phase modulation in fiber links with multiple optical amplifiers and dispersion compensators

• Published in: Journal of lightwave technology Vol. 14; no. 3; pp. 249 - 260
• Main Authors: Chiang, T.-K., Kagi, N., Marhic, M.E., Kazovsky, L.G.
• Format: Journal Article
• Language: English
• Published: New York, NY IEEE 01.03.1996; Institute of Electrical and Electronics Engineers
• Subjects: Applied sciences; Exact sciences and technology; Fiber nonlinear optics; Frequency response; Optical fiber amplifiers; Optical fiber dispersion; Optical fiber theory; Optical fibers; Optical modulation; Phase modulation; Semiconductor optical amplifiers; Stimulated emission; Systems, networks and services of telecommunications; Telecommunications; Telecommunications and information theory; Transmission and modulation (techniques and equipments); Phase modulation; Optical transmission; Optical telecommunication; Phase modulator; Wavelength division multiplexing; Performance analysis; Modeling; Optical fiber
• ISSN: 0733-8724; 1558-2213
• DOI: 10.1109/50.485582

We have theoretically and experimentally investigated the cross-phase modulation (XPM) effect in optical fiber links with multiple optical amplifiers and dispersion compensators. Our theory suggests that the XPM effect can be modeled as a phase modulator with inputs from the intensity of copropagating waves. The frequency response of the phase modulator corresponding to each copropagating wave depends on fiber dispersion, wavelength separation, and fiber length. The total XPM-induced phase shift is the integral of the phase shift contributions from all frequency components of copropagating waves. In nondispersive fibers, XPM is frequency-independent; in dispersive fibers, XPM's frequency response is approximately inversely proportional to the product of frequency, fiber dispersion, and wavelength separation. In an N-segment amplified link, the frequency response of XPM is increased N-fold, but only in very narrow frequency bands. In most other frequency bands, the amount of increase is limited and almost independent of N. However, in an N-segment amplified link with dispersion compensators, the frequency response of XPM is increased N-fold at all frequencies if the dispersion is compensated for within each fiber segment. Thus, the XPM-induced phase shift is smaller in systems employing lumped dispersion compensation than in systems employing distributed dispersion compensation.