Suppression of four wave mixing crosstalk components in DWDM optical systems

Increase in the data rate of fiber optic communication system is limited due to the nonlinear effects like self phase modulation (SPM) cross phase modulation (CPM) four wave mixing (FWM), stimulated Raman scattering (SRS) and stimulated Brillion scattering (SBS). Many investigations are carried to mitigate these effects and in multi channel systems, four-wave mixing (FWM) in optical fibers induces channel crosstalk and possibly degrades system performance. An optical orthogonal code is a family of (0,1) sequences with good auto and cross correlation properties The use of optical orthogonal codes enables a large number of asynchronous users to transmit information efficiently and reliably. This paper examines the fiber optic code division multiple access technique and proposes an alternative frequency assignment scheme to suppress the FWM crosstalk by allocating frequencies to a set of unevenly spaced channels determined by an optical spreading code. This scheme is advantageous than the previously mentioned frequency assignment schemes like reduced optical bandwidth requirements, more number of channels with null FWM crosstalk points