Vertically coupled microring resonators using one epitaxial growth step and single-side lithography.

A new concept for the fabrication of integrated microring resonators, requiring only one single epitaxial growth and two single-side lithographic steps, is proposed in what is the simplest fabrication scheme for vertical microrings published to date. The approach is based on two vertically stacked phase matched core layers. The effect of bus waveguide, coupling region and ring structure parameters is theoretically analyzed. Numerical calculations predict high performance devices with quality factors of over 10000. The scheme can feature both active and passive regions, allowing the fabrication of microring lasers.