Vertically Coupled Microdisk Resonators Using AlGaAs/AlOx Technology

In this letter, we report the first experimental demonstration of microdisk resonators that are vertically coupled to their buried access waveguides on III-V semiconductor epitaxial structures using an original fabrication process. The here-proposed and validated three-dimensional integration scheme exploits selective lateral thermal oxidation of aluminium-rich AlGaAs layers. Compared with the previously reported processing techniques, this new scheme is simpler as it does not require any planarization or substrate transfer steps. As a proof-of-principle demonstration of this approach, 250-μm diameter microdisk devices exhibiting quality factor reaching ~8500 have been successfully fabricated.