A piezoelectrically actuated four-port Mach-Zehnder switch with 30-mus
switching time and 0.25-dB insertion loss is demonstrated at a wavele
ngth of 1.3 mum. The worst-case cross talk is below -21 dB for an arbi
trary input polarization. The process of fabricating the switch from c
ommercial fiber couplers with length matching of the interferometer ar
ms is described.