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Fabrication and integration of high-Q Whispering-Gallery (WG) optical and optomechanical resonators

Fabrication of microresonators with large optical quality factors (> 106) is a challenging task and meanwhile an important requirement for many photonic devices and systems that use optical resonance for sensing, modulation, filtering, etc. An equally important task is the integration of these microresonators with planar optical waveguides and other photonic components without degrading their quality factor. We work on fabrication of novel high-Q microresonators (using new materials, geometries) as well as new monolithic and hybrid integration techniques. In optomechanical systems the mechanical quality factor of the microresonator also plays an important role in the performance of the device. A very challenging task is the design and fabrication of microresonators that can support both optical and mechanical modes with large quality factors. We work on novel configurations and fabrication techniques that enable high-optical quality and mechanical high-Q resonance in a a single structure with application in sensing, optomechanical oscillation and fundamental physics research. Optofluidic dorplet resonators are a sub-class of Whispering-Galley mode resonators that are specifically important for exploring nonlinear optical propetries of liquids and biosensing. We have created novle techniques for stabilizing and waveguide coupling to these resonators. 

- Free silica microtoroids

M. Hossein-Zadeh, and K. J. Vahala, “Free Ultra-high-Q microtoroid: a tool for designing photonic devices,  Optics Express, vol. 15(1), pp. 166-175, Jan2007.  

-Droplet resonator

M. Hossein-Zadeh, and K. J. Vahala, “Fiber-taper coupling to Whispering-Gallery modes of droplet resonators embedded in a liquid medium”, Optics Express, vol. 14(22), pp. 10800-10810, Oct 2006.

- Fluoride glass mid-IR microsphere  microresonators

B. Way, R. K. Jain, and M. Hossein-Zadeh, "High-Q Microresonators for Mid-IR Light Sources and Molecular Sensors",  Optics Letters, vol. 37, no. 21, pp. 4389-4391, 2012.

- Coupling via half-disk