Recent developments in micro/nano fabrication have resulted in mechanical devices with excellent optical and mechanical properties. Mechanical oscillators coupled to the electromagnetic mode of a cavity have emerged as an important new frontier in photonics, and have enabled interesting experiments in cavity opto-mechanics. A notable contribution that has come out of this area of research is the manifestation of parametric instability in such resonators, resulting in mechanical ampli cation and thereby oscillation of the mechanical mode driven purely by pressure of light. Such oscillators offer an all optical Radio Frequency (RF) source without the need for external electrical feedback. In his talk, he shall present a CMOS compatible fabrication process to design high optical quality factor opto-mechanical resonators in silicon nitride. The ring resonators designed in this process demonstrate low phase noise radiation pressure (RP) driven oscillations. Using integrated grating couplers and a waveguide to couple light to the micro-resonator eliminates 1/f^3 and other higher order phase noise slopes at close-to-carrier frequencies that are notoriously present in all other earlier demonstrations. In the second part of his talk, he shall describe a novel way of monolithic integration of electrostatic capacitive actuation with optical sensing using silicon opto-mechanical ring resonators and waveguides. The electrically excited mechanical motion is observed as an optical intensity modulation owing to high sensitivity of optical resonance frequencies to mechanical motion displacements. Using this modulator in a closed feedback loop, an Opto-Acoustic Oscillator (OAO) has been demonstrated. Choosing an ultra high quality factor optical resonance for the operation of this modulator results in simultaneous amplitude and frequency modulation of the laser light coupled to the resonator. He shall also present results on achieving GHz rate frequency modulation of continuous wave laser light of 1,550nm wavelength.
Siddharth Tallur graduated with a B.Tech. in Electrical Engineering at IIT Bombay in 2008. He is currently a Ph.D. candidate at the OxideMEMS Laboratory at Cornell University, Ithaca, NY, USA. His work focuses on understanding phase noise in hybrid oscillators and designing low phase noise RF opto-mechanical and opto-acoustic oscillators. Prior to joining Cornell University, he was serving as a Business Analyst at the global strategy consulting firm A.T.Kearney Ltd. in their Mumbai office. Outside the cleanroom and laboratory, he presides over the activities of the Electron Devices Society (EDS) and SPICMACAY at Cornell University. He enjoys playing the guitar and participates regularly in marathons and other long distance running events. His work on electro-optic frequency modulation was the recipient of the best student paper award at the IEEE Photonics Conference 2012 held in Burlingame, California. He was also recently nominated by the IEEE Photonics Society to receive the 2012 best student paper award from the U.S. Advisory Committee to the International Commission for Optics (USAC/ICO). He has also worked with the ApselLab in Cornell University and co-authored several papers on design and characterization of a low power ultra wide band (UWB) impulse radio transceiver.