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Monday, May 2, 2011 Allen 101X Auditorium 4:00 -­‐ 5:00 Surface Wave Optomechanical Oscillators Dr. Gaurav Bahl University of Michigan Abstract In a manner similar to the forces that we feel as a car goes around a curve, light is also known to apply centrifugal force when guided along a ring. In recent years, oscillators that exploit such optical forces to parametrically excite mechanical resonances in toroid-­‐ and disc-­‐shaped microstructures have emerged. These oscillators are promising candidates for compact frequency standards, as well as for various sensor applications. Our work at Michigan focuses on a new type of optomechanical oscillator that uses stimulated Brillouin scattering in ~100 um silica microspheres to inject acoustical phonons into a surface vibrational mode, and is arguably a phonon laser! What makes these oscillators particularly exciting is that a single microsphere can be used to controllably generate discrete mechanical frequencies ranging from 50 MHz up to nearly 12 GHz, limited primarily by the material properties. I will also discuss some of the engineering needs that still are to be met for "Photonic MEMS", and how conventional MEMS and microengineering can make significant contributions towards filling these technological gaps. Biography Gaurav Bahl received the B.Eng. degree in electrical engineering from McMaster University, Hamilton, ON, Canada, in 2005, and the M.S. degree and the Ph.D. degree in electrical engineering from Stanford University, Stanford, CA, in 2008 and 2010, respectively. His work at Stanford focused on studying dielectric charging in resonant MEMS and drift stability of encapsulated silicon microresonators. In 2008, he was with HP Laboratories, Palo Alto, CA, where he published on circumventing charging-­‐ related drift issues within the dielectrics of surface electrode actuators. Gaurav figured that a change in climate from sunny California would be “good for the soul” and moved to Michigan after his PhD to learn about experimental optics. He is currently a Postdoctoral Research Fellow at the Carmon lab at the University of Michigan, Ann Arbor, where he is developing optomechanical oscillators for frequency reference applications.