Description:

Title: Exploring nonreciprocity and high throughput sensing with optomechanical interactions

Speaker: Gaurav Bahl, UIUC, EECS Department

Abstract:

Microscale cavities that simultaneously exhibit high-Q optical and mechanical resonances are often employed for studying the coupling between light and vibration. The unique physics of these opto-mechanical systems enables many fundamental experiments in nonlinear optics, with analogies to condensed matter phenomena including cooling and induced transparency, and also for extreme-resolution sensing applications.However, all these systems are generally averse to fluids due to perturbation of refractive indices, scattering, absorption, and mechanical damping. Optomechanical systems have thus remained entirely solid-state till recently.

Our work has focused on two unique areas within optomechanics – (1) using Brillouin scattering for coupling optical fields to traveling acoustic waves in ultra-high-Q resonators [1]; and (2) on developing the first microfluidic optomechanical device [2] capable of high-throughput physical measurements on arbitrary flowing analytes.

In my talk I will discuss the underlying mechanisms of Brillouin Optomechanics and the applications that we have explored in parametric excitation and cooling of acoustic modes, and on induced transparency phenomena that enable nonreciprocal optical transmission[3]. Tangentially, we have also recently been exploring the physics of opto-mechano-fluidic interactions that enable extremely high-speed measurement of the mechanical properties of fluids and nanoparticles[4], only by using light. The new informational degrees-of-freedom provided by such opto-acoustic measurements can lead to surprising new sensor applications in the near future.

Refs.

[1] Bahl et al, Nat. Phys. vol.8(3), p.203, 2012

[2] Bahl et al, Nat. Comms. 4:1994, 2013

[3] Kim et al, Nat. Phys. vol.11, p.275, 2015

[4] Han et al, Optica, (in print) vol.3(6), 2016.

Bio

Dr. Gaurav Bahl is an Assistant Professor of Mechanical Science and Engineering at the University of Illinois at Urbana-Champaign (UIUC), and an Affiliate Faculty in the Department of Electrical and Computer Engineering. Dr. Bahl received his PhD and MS degrees in EE from Stanford University in 2010 and 2008, and BEng degree in ECE from McMaster University in 2005. He has authored the first experimental papers on parametric excitation and optical cooling through Brillouin Optomechanics, and on Opto-Mechano-Fluidic oscillators. His work on Brillouin systems (cooling and microfluidics) has been featured as a “(top-30) significant development in optics” for two years in a row in the Optics in 2012 and Optics in 2013 special issues of the OSAs monthly Optics & Photonics News magazine. Additional commentary by editors and prominent researchers on the significance of his Brillouin optomechanics work has appeared in Nature Physics, Nature Photonics, and many technical news outlets. Dr. Bahl is also a recipient of the US Air Force Young Investigator Award in 2015.

Host: Selim M Shahriar, Brian Odom

Keywords: Physics, Astronomy, AMO