Hello, dear Community fellows!
This post is about nonlinear effects. Please see more details below.
BACKGROUND INFORMATION
In a common fiber communication system, the light intensity in the fiber is low. In this case, the fiber is a linear medium. The attributes of the fiber linearly vary with the light field. With the continuous development of the DWDM and EDFA technologies, one fiber can transmit more and more wavelengths and the incident optical power becomes larger and larger. When the light intensity of incident optical power is high, the fiber is subject to nonlinear effects.
The nonlinear effect depends on the light intensity and light-fiber interaction length. Because the optical power loss of the fiber is small, the high light intensity persists in a long distance. This greatly increases the light-fiber interaction length and makes the nonlinear effect the decisive factor that limits the system performance.
In addition, some nonlinear effects are tightly relevant to dispersion; the nonlinear effect intensity varies with the dispersion magnitude. Hence, the final impact of nonlinear effects on the system is complex.
NONLINEAR EFFECTS IN TRANSMISSION FIBER
In a high-rate transmission system, especially in a DWDM system with many channels and small channel spacing, the nonlinear effect is one of the major factors that limit the system performance. The nonlinear effects in a transmission fiber present the following features:
diversity - the nonlinear effects are classified into stimulated scattering (including stimulated Brillouin scattering (SBS) and stimulated Raman scattering (SRS)) and Kerr magnetooptical effects (including SPM, cross-phase modulation (XPM) and four-wave mix (FWM));
complexity - the nonlinear effects result from the interaction between light and transmission media. The interaction relationship is complex because it involves many factors;
tight dependency on fiber parameters such as dispersion and effective cross section area: Many nonlinear effects are tightly relevant to dispersion. In addition, increasing the effective cross section area of the fiber can decrease the optical power density in the fiber and thus reduce the nonlinear effects;
tight dependency on optical power - the nonlinear effects result from the interaction between light and transmission fiber. The nonlinear effects occur only when the optical power value crosses the threshold. The threshold varies with the nonlinear effect type and the actual conditions. decreasing the optical power is one of the means to reduce nonlinear effects.
This would be all on nonlinear effects. Thanks for reading this post!
