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Tellurite glasses have promising material properties in applications for linear and nonlinear integrated optical devices. Tellurite glasses have high rare earth solubilities for applications in rare earth doped lasers as well as high nonlinear refractive indices, Raman gain coefficients and acousto-optic figures of merit. However, it is difficult to take advantage of tellurite glass properties in silicon photonics, as the waveguiding materials available for use in silicon photonic devices are typically limited to silicon, silicon dioxide, silicon nitride, and germanium. Here, we report on a tellurium oxide whispering gallery resonator, integrated onto a silicon photonic chip and coupled to a silicon waveguide. The silicon waveguides are fabricated using a standard foundry process and the cladding oxide is etched in a ring shape with precise alignment to the bus waveguides at gaps from 0.2 to 1.0 μm to form the cavity. Post processing deposition of a tellurium oxide film coats the bottom of the etched oxide cavity, forming a tellurium oxide waveguiding layer, into which light can be coupled from the silicon waveguide. A resonator with a radius of 40 μm and a 1.1-μm-thick tellurium oxide coating is measured to have an internal Q-factor of greater than 1E5. These results illustrate the potential for integration of tellurite glass devices into silicon photonic microsystems. Applications of this cavity structure in optical sensing, design considerations and methods to improve performance will be discussed.
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