Bahl tackles Photonic MEMS special topics course

Despite his ongoing research in microcavity opto-mechanics—in which optical and mechanical systems interact with each other—Assistant Professor Gaurav Bahl said that one of his greatest challenges in the Fall 2012 semester was keeping up with lecture presentations for his class. Half of his office wall was blanketed in color post-its, which showed his course plans for every week of the semester. After accepting his position in MechSE in April 2012, Bahl began to prepare course material for his Fall 2012 special topics course, Photonic MEMS (micro-electro-mechanical systems).

"Initially, because teaching a class this size was new to me, I was spending 10 to 20 hours (of preparation) per hour of lecture," Bahl said. "That's not a very good number, because that way no one can be really effective. Now, it's more like two to three hours per hour of lecture, or sometimes even less."

Although Bahl's class is open to all students, only graduate students were enrolled in his first semester. However, he hopes that more undergraduates will enroll next fall, when he expects to offer the course again. The class this year consists of 14 mechanical engineers and two electrical engineers, which is a new experience for him given that he studied electrical engineering throughout his undergraduate, graduate, and postdoctoral education.

"The system of teaching has been sort of reversed for me a little bit," Bahl said. "However, I can bring points of view that we don’t normally see in mechanical engineering very often, especially in the subject area of optical physics."

When he reflects on the experiences that led him to become a professor in MechSE, he admits that his work with mechanical engineering began far before teaching Photonic MEMS. During his time as an undergraduate, he worked with mechanical resonators in a MEMS-focused research group. In his graduate studies, he worked on micromechanical oscillators in a research group led by a mechanical engineer professor. Most recently, Bahl looked at the interaction of light with mechanical devices during his postdoctoral studies.

"Throughout my education there has been some element of mechanics present," Bahl said.

He also uses elements of mechanics in his current research, as he explores using photons (particles of light) to create mechanical deformations and vibrations. Most recently, towards the end of his postdoctoral studies, he used optomechanical techniques to excite ultra-high frequency mechanical vibrations in a microfluidic channel.

"Now, we have a completely new way in which we can couple light with a fluid, not just a solid object," Bahl said. "The flows and the acoustic waves within a fluid, we can couple that directly to light as well."

Bahl defined other applications of his research as gyroscopes, oscillators, lasers, and nonlinear optical devices. His recent work on using light to cool a sound wave, "Observation of spontaneous Brillouin Cooling," which appeared originally in Nature Physics (Vol. 8, No. 3, pp. 203-207, 2012), is featured in the OSA Optics and Photonics News magazine as one of the top 30 innovations in "Optics in 2012." (http://www.opnmagazine-digital.com/opn/201212#pg45)