Effects of Shallow Suspension in Low-Loss Waveguide-Integrated Chalcogenide Microdisk Resonators

On-chip waveguide-integrated suspended microcavity resonator as a good sensing element is constantly pursued combining with the advantages of an optical material to enhance device performance. In this work, low-loss waveguide-integrated suspended Ge11.5As24Se64.5 microdisk resonators have been successfully demonstrated using an optimized etching recipe. The realization of propagation loss down to 0.48 dB/cm verifies the low-loss characteristic of chalcogenide glass rectangular waveguide. An optical loaded quality factor of 1.1 × 10
⁶
for the no suspended microdisk resonator, approaching to the highest figure (1.2 × 10
⁶
) so far reported in planar chalcogenide optical devices, is obtained experimentally to reveal the natural evolution of high quality chalcogenide glass membrane during the engineering of shallow suspension configuration. By comparing with the scattering loss of mode in no suspended case, the contributions of bottom roughness scattering to the optical losses increase exceeding 50% in the shallowly suspended counterparts. The optimization and optical losses analysis of the waveguide-integrated suspended chalcogenide microdisk resonators are helpful to further estimate its potentials in the emerging stress or strain sensors.