Optically Controllable Gray-Level Diffraction from a BCT Photonic Crystal Based on Azo Dye-Doped HPDLC

Shing-Trong Wu¹, Chung-Hung Liu¹, Jui-Hsiang Liu², Ming-Hsien Li^3*, Andy Ying-Guey Fuh^1,3,4

¹Department of Physics, National Cheng Kung University, Tainan.
²Department of Chemical Engineering, National Cheng Kung University, Tainan.
³Department of Photonics, National Cheng Kung University, Tainan, Taiwan.
⁴Advanced Optoelectronic Technology Center, National Cheng Kung University, Tainan.

DOI: 10.4236/opj.2014.410028                

Abstract

We investigated optically controllable gray-level diffraction from a body-centered tetragonal photonic crystal that was based on an azo-dye-doped holographic polymer dispersed liquid crystal. The sample is fabricated by use of two-beam interference with multi-exposure. Bichromatic pumping beams at various intensities were used to pump the sample to change the concentration of the cis isomer and, in turn, modulate the effective index of the photonic crystals as well as their diffraction intensity. Three pumping processes were utilized to produce gray-level switching of diffractive light. This study demonstrates the optimum gray-level to be 15-level of up-step and down-step. The simulation of the diffraction intensity under bichromatic pumping sources was also studied.

Keywords

All Optically Control, Gray-Level, Photonic Crystals, HPDLC

Conflicts of Interest

The authors declare no conflicts of interest.

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