Strong optical non-linearities for efficient all-optical switching in GaAlAs waveguides

The light intensity transmission of GaAlAs strip waveguides is sensitively dependent on the strength of the electric field inside the waveguide, when the photon energy is close to the band gap (Franz-Keldysh effect). In a waveguide embedded in a pn-junction the transmitted light itself induces the field changes through the photoelectric effect. This photo-induced Franz-Keldysh effect causes a non-linear intensity transmission of the waveguide. Light power levels far below 1 mW are sufficient to give strong non-linearities. Possible application schemes for modulation and all-optical switching in integrated optics and optoelectronics are discussed.