Light interacting with metallic and dielectric structures can produce various interesting optical effects. Structural color is one of them, where the structure-property relationship determines the optical response, more so than the constituent materials. Structural colors can be produced by exploiting optical resonances in 1D, 2D and 3D structures, offering advantages over conventional colored pigments such as high brightness, durability, and environmental safety and sustainability. The scalable nanopatterning technique is the key to enabling large-area manufacturing for sub-micron structures. Simpler yet is a multilayer structure that can be realized by vapor deposition, with a wide range of applications. Analysis shows that color chromaticity can be controlled by adjusting the absorption and radiation loss in an optical cavity. In the past, human experts performed optical design manually based on accumulated experience and physical intuitions. This is especially true for photonic inverse design, which finds the appropriate photonic structures with the desired optical functions. We show that the deep learning approach can automatically design sophisticated structures to satisfy the design objective, and can facilitate researchers to gain insight on the working mechanism. For cost-effective fabrication, we explored the solution process (e.g. electrochemical deposition and dip-coating) to form optical thin film structures, which can yield both primary and subtractive colors depending on the morphology of the thin metal layer.
L. Jay Guo is a Professor of Electrical and Computer Engineering at the University of Michigan, where he joined in 1999 after his Ph.D. and postdoc. His lab is involved in interdisciplinary research, with activities ranging from polymer-based photonic devices and sensor applications, flexible transparent conductors, nanophotonics & structural colors, hybrid photovoltaics and photodetectors, to nanomanufacturing technologies, and are contributed by students from Electrical Engineering and Optics, Macromolecular Science & Engineering, Applied Physics, and Mechanical Engineering. He has over 280 journal publications; with citations over 30,000 times, and an H-index of 85 (by google scholar). His professional service includes Associate Editor of Optica (till 2021); and is currently a member of the Editorial Advisory Board of Advanced Optical Materials, and Opto-electric Science. His entrepreneurial activities include co-founding two startup companies to commercialize technologies from his lab.