报告题目：Interaction of light with nanostructures suspended in liquid: from thermal lens effect to photoacoustic laser streaming
报告题目：Interaction of light with nanostructures suspended in liquid: from thermal lens effect to photoacoustic laser streaming
报告人：休斯顿大学Jiming Bao副教授
时间：5月28日上午10:00-11:00
地点：教三-440
Abstract: Due to the ease of synthesis and handling, nanomaterials are often dispersed in transparent solvents to study their interaction with light. Nonlinear optical phenomena such as saturable absorption and self-phase modulation are observed in many nanomaterial dispersions, and are often ascribed to their intrinsic nonlinear optical properties. In this talk, I want to point out that the effects of solvents cannot be overlooked, in most cases, solvents can introduce unintended consequences. I will show you two cases to illustrate this point. In the first case, concentric diffraction ring patterns are observed when a laser beam passes through a graphene dispersion. This phenomenon was explained as a manifestation of a large third-order nonlinear effect of graphene. I will argue that such diffraction ring is actually caused by the thermal lens effect of the solvent and I will show you how to distinguish it from the intrinsic nonlinear self-phase modulation. In the second example, while looking for similar ring pattern in Au nanoparticle suspension, we discovered a completely new phenomenon: photoacoustic laser streaming. The laser beam drives the water with such a large force that a water jet is created. This is a new optofluidics principle that combines photoacoustics with acoustic streaming.
Biography: Dr. Bao is an associate professor of Electrical and Computer engineering at the University of Houston. He graduated from Zhejiang University with B.S. and M.S. in physics in 1992 and 1995, respectively. He obtained his Ph.D. in applied physics in 2003 from the University of Michigan, he then did post-doctoral research at Harvard University before joining the University of Houston in 2008 as an assistant professor. His current research covers many interdisciplinary topics ranging from solar energy conversion to fiber optic sensing.
