
256 Optical Fiber Communication Systems with MATLAB
®
and Simulink
®
Models
caused
by the nonlinear effects. The DPSK optical power spectra, however, do not contain
these high power frequency components. (2) RZ pulses are more sensitive to ber disper-
sion
because of their broader spectra. In particular, RZ33 pulse type has the broadest spec-
trum
at the point of −20 dB down from the peak. This property of the RZ pulses thus leads
to faster spreading of the pulse when propagating along the ber. Thus, the peak values
of the optical power of these CSRZ or RZ33 pulses decrease much more quickly than the
NRZ counterparts. As a result, the peak optical ...