Hybrid-integrated symmetric Mach-Zehnder all-optical switches and ultrafast signal processing

Symmetric Mach-Zehnder (SMZ) type all-optical switches are discussed. The SMZ type all-optical switches feature the so-called differential phase modulation scheme to achieve a speed unrestricted by efficient, thus usually slow nonlinearities. In these switches, semiconductor optical amplifiers (SOAs) are often used to realize low optical power switching. We discussed SOAs from a view point of all-optical switch applications, rather than amplifier applications. Finally, all-optical signal processing experiments are discussed with the SMZ type all-optical switches. These include ultrafast demultiplexing of 336Gb/s signal pulses and random operations at 42 Gb/s for all-optical logic operation and wavelength conversion.