Ultrafast (/spl sim/1 THz) 1.55 /spl mu/m all-optical switch using intersubband absorption in InGaAs/AlAs/AlAsSb coupled quantum wells

We report on the first all-optical switching operation of intersubband absorption at an optical communication wavelength (/spl sim/1.55 /spl mu/m), which was achieved by InGaAs/AlAs/AlAsSb coupled quantum wells. The switching energy was as low as 27 pJ.