Fabrication of horizontal hollow slot waveguides in a microring resonator using Nb ₂ O ₅ for sensor devices

Abstract Horizontal slot waveguides allow light to be partially confined in the low index region. Furthermore, it is possible to realize a sensor that utilizes the change in effective refractive index depending on the state of the material in the hollow slot structure. We present a method for fabricating microring resonators using Nb2O5 horizontal hollow slot waveguides for sensor devices. We used a process using an electron beam lithography technique for forming hollow slot region. Hollow slot waveguides were formed in the ring resonator by selective etching using the patterned PMMA as a protective film. The resonant characteristics were obtained by using the fabricated microring resonator using Nb2O5 horizontal hollow slot waveguides. As a preliminary study, resonant characteristics dependent on the material filled in the horizontal slot region were also obtained.