High-speed InGaAlAs-InAlAs MQW directional coupler waveguide switch modules integrated with a spotsize converter having a lateral taper, thin-film core, and ridge

Fully packaged 2/spl times/2 and 4/spl times/4 semiconductor optical switch modules are successfully developed by integrating spotsize converters (SSCs) consisting of lateral tapers, thin-film cores, and ridges in InGaAlAs-InAlAs multiple quantum-well (MQW) directional coupler waveguide switches in the 1.55-/spl mu/m wavelength region. Good reproducibility is obtained for the perfect coupling length of the directional coupler by appropriately designing the ridge width and gap of strip-loaded optical waveguides and by making use of the Cl/sub 2/ reactive-ion-beam-etching and successive wet-etching. Since the switching time is sufficiently short (<70 ps, which is limited by the driver speed) for the 4/spl times/4 switch module, no bits are lost during a 10-Gb/s switching experiment at a wavelength of 1.55 /spl mu/m.