Inverted-wedge silica resonators for controlled and stable coupling

Silica microresonators with an inverted-wedge shape were fabricated using conventional semiconductor fabrication methods. The measured quality factors of the resonators were greater than 106 in 1550 nm band. Controllable coupling from undercoupling to the overcoupling regime through the critical coupling point was demonstrated by horizontally moving a fiber taper while in touch with the top surface of the resonator. The thin outer ring of the resonator provided a support for the fiber taper leading to robust stable coupling.