Dense wavelength division multiplexing (DWDM) systems are highly attractive in today's communication scenario, since they offer large transmission capacity and also achieve higher spectral efficiency. A scheme to reduce four-wave mixing (FWM) cross talk by using optical spreading code-based channel frequency allocation to a set of unevenly spaced channels is proposed. This assignment scheme provides several advantages over previously proposed schemes. The performance of this scheme for equal and unequal spaced channels of 4- and 16-channel DWDM systems is analyzed for various coding formats, including return to zero, nonreturn to zero, carrier-suppressed return to zero, and vestigial-sideband return to zero. It is observed that unequal channel spacing provides an improvement in the Q factor for all coding formats, and it is also noted that the vestigial-sideband return to zero technique is more tolerant to FWM cross-talk components.
© 2007 Optical Society of America
Original Manuscript: October 8, 2006
Revised Manuscript: November 1, 2006
Manuscript Accepted: November 14, 2006
Published: January 25, 2007
A. V. Ramprasad and M. Meenakshi, "Performance of NRZ, RZ, CSRZ, and VSB-RZ modulation formats in the presence of four-wave mixing effect in DWDM optical systems," J. Opt. Netw. 6, 146-156 (2007)