We compare the interchannel four-wave mixing (FWM) in dense wavelength division multiplexing (DWDM) systems with continuous waves, quasi-continuous waves and ultrashort pulses. The differences are theoretically analyzed for the three inputs. We investigate the FWM conversion efficiency as a function of the channel spacing, the fiber length, the single bit energy and the pulse width. It is shown that the FWM effect in DWDM systems with quasi-continuous waves is the strongest and with ultrashort pulses is the lowest among the three cases. The FWM conversion efficiency changes periodically with the propagation length, and it is approximately an exponential function of the single bit energy. The performance of the pulse FWM effect versus the pulse width is different from that of the quasi-continuous wave FWM, which may be one possible way to suppress the interchannel FWM.
Bandwidth scaling of a phase-modulated continuous-wave comb through four-wave mixing in a silicon nano-waveguide