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 x 2 and 4 x 4 semiconductor optical switch modules are suc cessfully developed by integrating spotsize converters (SSC's) consisting o f lateral tapers, thin-film cores, and ridges in InGaAIAs-InAIAs muliple qu antum-well (MQW) directional coupler waveguide switches in the 1.55-mu m wa velength region. Good reproducibility is obtained for the perfect coupling length of the directional coupler by appropriately designing the ridge widt h and gap of strip-loaded optical waveguides and by making use of the Cl-2 reactive-ion-beam-etching and successive wet-etching, Since the switching t ime is sufficiently short (<70 ps, which is limited by the driver speed) fo r the 4 x 4 switch module, no bits are lost during a 10-Gb/s switching expe riment at a wavelength of 1.55 mu m.