Mode expanded optical switch in resonant vertically coupled waveguides

We propose and demonstrate a novel expanded mode voltage controlled optical switch based on electrorefraction and electroabsorption in resonantly coupled tapered vertical waveguides. The device was grown in a single standard epitaxial growth and was processed using conventional fabrication techniques. A 200-μm-long mode transformation region was used for expanding the mode and optical switching. Greater than 20-dB switching contrast ratio was obtained with a reverse bias of less than 1 V. Reduced far-field divergence angles (8/spl deg/×24/spl deg/) were also achieved. With good contrast ratio at low voltage bias and an inherent expanded mode, this device shows promise for low-cost optoelectronic switching applications.