nonlinearities. Fibers have an instantaneous response to pulses but have
limited nonlinearity, even in specially designed photonic crystal fibers;
hence long lengths are required. PPLN requires intermediate lengths, and
very fast conversion (40–160 Gbps) has been demonstrated.
Considerable research has been done in the area of single-wavelength subsystems,
and e.g., advanced all-optical regenerative schemes at bit rates beyond 100 Gbps
have been recently proposed in Ref. [47], as well as well-reported
demonstrations at 40 Gbps [48]. Multiwavelength all-optical regeneration, if
feasible, will dramatically decrease the cost of DWDM transmission links.
A number of techniques are currently being considered, e.g., (a) through the
mechanism of self-phase ...