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In this paper we present results from our research into the use of microgel-based photonic crystals in an optical tagging application. The basis for this research is the phenomena of self-assembly of hydrogel nano- and microparticles (i.e., microgels) into colloidal crystal Bragg reflectors. Previous research has demonstrated the assembly of Bragg structures that are sensitive in the visible spectral region. This current research focuses on the extension of this process into the infrared regime and the use of these infrared-sensitive structures in the creation of an optical tag. In particular, the research effort emphasizes two primary areas: the development of nanoparticles that are infrared-sensitive and the casting of thin films comprised of these particles. We will also present theoretical data on the optical and physical characteristics of thin films comprised of these particles. This paper will present an overview of the program, outline the processes and issues addressed during our initial efforts in creating these infrared sensitive structures and present a summary of the computational results based on the theoretical analyses.
optical tagging, Crystals, Distributed Bragg reflectors, Nanoparticles, Particles, Photonic crystals, Thin films
Atomic, Molecular and Optical Physics | Chemistry | Materials Chemistry
J. Michael Cathcart ; L. A. Lyon ; Marcus Weck and Robert D. Bock. "Application of microgels for optical tagging", Proc. SPIE 5403, Sensors, and Command, Control, Communications, and Intelligence (C3I) Technologies for Homeland Security and Homeland Defense III, 774 (September 15, 2004); doi:10.1117/12.542978; http://dx.doi.org/10.1117/12.542978