1.55-μm picosecond all-optical switching by 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 μm). The 1.55-μm intersubband absorption was achieved by InGaAs-AlAs-AlAsSb coupled quantum wells. A switching operation on an ultrafast signal (equivalent to 1 THz) was successfully demonstrated with a control pulse energy as low as 27 pJ.