Athermal Silicon-on-insulator ring resonators by overlaying a polymer cladding on narrowed waveguides

Athermal silicon ring resonators are experimentally demonstrated by overlaying a polymer cladding on narrowed silicon wires. The ideal width to achieve athermal condition for the TE mode of 220nm-height SOI waveguides is found to be around 350nm. After overlaying a polymer layer, the wavelength temperature dependence of the silicon ring resonator is reduced to less than 5 pm/degrees C, almost eleven times less than that of normal silicon waveguides. The optical loss of a 350-nm bent waveguide (with a radius of 15 mu m) is extracted from the ring transmission spectrum. The scattering loss is reduced to an acceptable level of about 50dB/cm after overlaying a polymer cladding. (C) 2009 Optical Society of America