Zhixiong "James" Guo

Assistant Professor
Department of Mechanical and Aerospace Engineering
Rutgers, The State University of New Jersey

Laser Radiation and Energy Transport in Emerging Bio-Applications

In this talk, I will briefly introduce the following two research topics: (1) modeling of ultrafast laser radiation transport and heat transfer in biological tissues for applications in laser biomedical imaging and surgery; and (2) radiation transport in nanostructured optical microcavities used for biomolecular probing. In the first topic, we will emphasize on the modeling of ultrashort-pulsed laser radiation propagation in turbid biological tissues, the associated hyperbolic phenomena of heat conduction, and the concept of optical tomography for imaging of tumors. In the second topic, we will discuss the nanoscale gap effects on whispering-gallery mode (WGM) optical microresonances and energy storage for the design and nanofabrication of WGM-based microsensors. WGMs describe resonant electromagnetic modes of photons that circulate in well-defined trajectories inside a microcavity. Photon tunneling between the cavity and light-delivery coupler is strongly dependent on the gap dimension. Under resonance, an enhanced radiation field exists inside the periphery of the cavity. A very strong evanescent field will then arise. Its strength decays exponentially with increasing distance from the surface up to the order of the optical wavelength involved. This evanescent field will certainly interact with target biomolecules adsorbed or covalently attached to the microcavity. Since WGMs are morphology-dependent, this molecule-radiation interaction will induce a change in the WGM resonant frequencies. In other words, a shift or broadening (narrowing) or intensity change in the resonances signifies an altered WGM microcavity environment.

Zhixiong Guo is an Assistant Professor of Mechanical and Aerospace Engineering at Rutgers University-New Brunswick since joining in 2001. He received his B.S., M.S., and Doctorate, all in Engineering Physics, from Tsinghua University, Beijing, in 1989, 1991 and 1995, respectively. Then he worked as a Research Fellow in Korean Advanced Institute of Science and Technology (South Korea, 95-96) and a Research Associate in Tohoku University (Japan, 96-99). From 1999 to 2001, he worked as a Research Staff Member in Polytechnic University (a.k.a. Brooklyn Poly), NY, where he completed his Ph.D. in Mechanical Engineering in the same time period. His research interests include radiation-matter interactions, laser applications in biology and medicine, thermal radiation, and micro/nanoscale heat transfer. Currently he is focusing on integrating nanophotonics with biotechnology, and conducting emerging technological applications such as MEMS/NEMS sensors, biomedical imaging and sensing at the molecular level. His research is funded by the NSF, NASA, NIH and other sources. He is the author or co-author of over 80 scientific publications; and an active member in ASME, OSA, and SPIE.

Friday, April 28, 2006, at NOON
ETC 7.146

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