Ultrafast polarization‐discriminating Mach‐Zehnder all‐optical switch

We propose a polarization‐discriminating Mach‐Zehnder (PDMZ) all‐optical switch. The switching speed of this PDMZ all‐optical switch is not limited by the slow relaxation time of highly efficient incoherent nonlinearities. We demonstrate a squarelike modulation characteristic, which is necessary in most switching applications, at a switching speed (on‐off time) of 40 ps. We also demonstrate ultrafast switching at a detector limited speed of ∼8 ps.