Nanomaterials and nanostructures for sensing, lasing and photodynamic therapy applications

Bobo Gu

The Institute for Lasers, Photonics and Biophotonics, The State University of New York at Buffalo

Abstract:

Nanotechnology is a technology that deals with the physical properties and phenomena of nanomaterials and nanostructures. In this talk, I will introduce some nanomaterials and nanostructures including self-assembled nanofilm, sub-wavelength metallic grating and ZnO nanoparticles, which have been experimentally demonstrated for sensing, lasing and photodynamic therapy applications.

As we know, some nanomaterials can sense the external environmental changes. Thus, the environmental changes can be interrogated when combining the functional nanomaterials and sensing platform. In this work, we functionalized the fiber-optic sensors with nanomaterials by the electrostatic self-assembly technique. Based on the swelling, association characteristics of the nanomaterials, the proposed sensors can perform pH sensing, relative humidity sensing, metal ions sensing, etc.
Such a miniaturized and reusable sensor is very promising technology for environmental pollution monitoring applications. ZnO is another functional nanomaterial, which has widespread applications. More importantly, the ZnO nanoparticles possess large second and third order nonlinearities, enabling the production of SHG, SFG and FWM, which could be successfully applied for photodynamic therapy (PDT). PDT is a theranostic modality that employs the photosensitizers to generate the reactive oxygen upon the irradiation of light for local treatment of disease. However, most of the available photosensitizers are activated by the visible light, it limits the penetration depth in tissue. We experimentally demonstrated the activation of photosensitizer by in suit SHG in targeting ZnO nanoparticles, and the PDT effect is enhanced by in suit SHG. Whispering gallery mode (WGM) resonator has been applied to many fields of applications including nanolasers, nanosensors and nanofilters. However, the traditional coupling devices including prism, tapered fiber, fiber tip, etc., are usually fragile and unstable. In this work, the nanostructure i.e. sub-wavelength metallic grating is experimentally demonstrated to enable efficient coupling in the WGM resonator for the first time.  The Fano resonance is also observed due to the interaction between the high-Q WGM and direct reflection of the grating. The Fano resonance can provide the feedback for the lasing cavity to form the narrow linewidth laser. Combining the narrow linewidth laser and high-Q WGM resonator, FWM is also observed in the proposed setup.

About the Speaker: 

Bobo Gu is a postdoctoral fellow at The State University of New York at Buffalo. He received his PhD in Optical Engineering from Zhejiang University in 2012, where his research focus is in the area of self-assembled nano-film for chemical sensing. In 2010, he studied at the Technical University of Denmark as a visiting student for one year, where his research work focuses on nonlinear optics. After PhD, he continued his research at Nanyang Technological University as a research fellow for two and a half years. At Nanyang Technological University, he developed his expertise in design and fabrication of sub-wavelength metallic grating for whispering gallery modes excitation. Then he joined The State University of New York at Buffalo as a postdoctoral fellow in 2014, where his research interests focus on the nanomaterials for bioimaging and therapy. He has published over 30 scientific papers, and he also holds a number of patents. Currently, his research interests include nonlinear optics, nanophotonics and biophotonics.

时间：2015-6-5 星期五下午1：30

地点：光学楼525教室