Error-free all-optical wavelength conversion at 168 Gb/s, which is the high
est repetition rate ever reported, has been achieved by using a Symmetric-M
ach-Zehnder (SMZ)-type switch. Low-power-penalty 84-Gb/s operation is also
demonstrated. The push-pull switching mechanism of the SMZ switch enables s
uch ultrafast operation based on cross-phase modulation associated with the
carrier depletion in a semiconductor optical amplifier. The configuration
of the Delayed-Interference Signal-wavelength Converter, which is a simplif
ied variant of the SMZ switch, is used in this experiment.