Suspended Si ring resonator for mid-IR application.

In this Letter we fabricate and characterize suspended silicon (Si) waveguides and ring resonators for mid-infrared wavelength range. Both tunable laser and thermal tuning are used to cover wavelength ranges near 5.2 and 3.4 μm. The loaded quality factors are estimated at 2700 at 5.2 μm and 7900 at 3.4 μm. Heat induced spectrum distortion is observed. Absorption loss is analyzed based on the spectrum distortion, simulation, and all-optical modulation. It is shown that main loss comes from scattering at surface and should be possible to reduce by improving fabrication process.