InGaAs-AlAs-AlAsSb coupled quantum well intersubband transition all-optical switch with low switching energy for OTDM systems

We report a novel intersubband transition all-optical switch with low switching energy using InGaAs-AlAs-AlAsSb coupled double quantum wells (C-DQWs) with AlAs spacer layers. Very low saturation energy density of 34 fJ/μm
²
was observed for bulk transmittance with wavelength of 1.62 μm. Using a waveguide, whose core is 93 periods of the C-DQWs, an all optical switch with a low switching energy of 10 pJ for 10-dB extinction ratio was realized.