All-optical switching between modes of a GaAs/GaAlAs multiple quantum well waveguide

A strain-induced multiple quantum well waveguide which can support two transverse modes in the plane normal to the quantum wells was excited in the TE mode by 350-ns-long probe pulses of low intensity from a dye laser tuned to a wavelength of 886 nm. A laser diode emitting at 850 nm was used in order to switch the 886 nm light between two positions at the exit facet of this overmoded waveguide. The switching mechanism has been shown to be non-thermal in origin.