报告人：Iam Choon Khoo 教授
题目：Liquid crystalline photonic crystals for high efficiency holographic recording with optically prolonged memory and slow light generation with short laser pulses
Liquid crystals possess extremely large optical nonlinearities that can be used in conjunction with various nano-structures and lasers ranging from the femtoseconds to CW operations, due to their extraordinarily large individual (organic) molecular nonlinearities that response in the sub-picoseconds time scale and collective crystalline optical nonlinearities that response in milliseconds –nanoseconds [1,2]. This presentation is focused on recently obtained results of high efficiency holographic recording with blue phase liquid crystals that exhibit intriguing optically prolonged memory effect, and femto-seconds slow light generation with cholesteric liquid crystals [1, 2]. We will discuss the mechanisms/techniques that enable these intriguing phenomena.
1. C.W. Chen et al, & I. c. Khoo “Slowing ultrafast (600 femtoseconds) laser pulse with a 550μm-thick cholesteric liquid crystal,” Optical Materials Express, Vol. 7, Issue 6, pp. 2005-2011 (2017)
2. I.C. Khoo et al, “High efficiency holographic Bragg grating with optically prolonged memory,” Sci. Rep. 6, 36148; (2016)
Dr. Khoo is internationally known for his pioneering and leading work in liquid crystals, and in nonlinear optical phenomena and applications. He has been a faculty member at Penn State since 1984, where he has established and directed the Nonlinear Optics and Liquid Crystal Research Laboratory. Over the years, his laboratory has received research funding from various Government agencies including:- the National Science Foundation, Defense Advanced Research Projects Agency, Navy Air Development, Air Force Office of Scientific Research, Air Force Phillips Laboratory, and the Army Research Office. Prof. Khoo is a Fellow of the Optical Society of America, IEEE, The United Kingdom Institute of Physics and The Electromagnetic Academy. He has previously served a three-year term as Vice President of Technical Affair for the IEEE-Lasers and Electro-Optics Society and as Chair of the United States Advisory Committee/International Commission for Optics of the US National Academies. He is the author, co-author of over 600 technical publications and several books on nonlinear optics and liquid crystal optical physics. Ongoing research activities in his laboratory and collaborative research programs are centered on nonlinear and electro-optical properties of liquid crystals and nano-structured novel refractive metamaterials, and studies of optical wave mixings, optical switching and modulation, optical limiting and sensor protection enabled by unique properties of these optical materials.