FDTD Analysis of Light Control by Magnetically Oriented Guanine Crystal Plates

3-D simulations of electromagnetic field by finite difference time-domain (FDTD) algorithm were helpful for analyzing propagations of electromagnetic wave. In industrial fields, FDTD simulations are necessary to design telecommunication devices. Furthermore, structures of photonic crystal and light transmissions in nanoscale-microscale structures of it were also actively studied and FDTD simulations are also utilized for designing of it. Many bioorganisms produce biophotonic crystals that have nanocyclic structures. For example, guanine crystals stacked in fish skin strongly reflect light to camouflage their body. Our group studies this crystal to apply for development of biogenic microoptical devices. In this paper, we analyzed light scattering on guanine crystal by FDTD simulations with model structure of the crystal. Rotating the crystal axis to the incident light, the direction of reflected light was simulated. Distributions of strength of light reflectance on the surface of crystal plane were also analyzed and compared with three kinds of incident wavelengths. Results suggested the relations of directivity of the reflected light with the incident angle of light irradiation to the crystal.