Compact low-loss vertical resonant mode coupling between two well-confined waveguides

The authors have achieved low-loss vertical mode transfer in an ultra-compact device between a 1.55 mu m InGaAsP QW active waveguide and a well-confined passive waveguide using a 100 mu m long taper. The radiation loss during the transfer was measured to be < 0.3dB. The device was fabricated using a single epitaxial growth and conventional fabrication schemes. This approach will lead to a new platform technology for integrating active and passive photonic devices.