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Optical diode based on unidirectional transmission of defect modes in cholesteric liquid crystals: A simulation study

JIUN-YEU CHEN1,*

Affiliation

  1. Department of Electronic Commerce, Hsing Kuo University of Management, 89, Yuying Street, Tainan 709, Taiwan

Abstract

A photonic system composed of two cholesteric layers with the same pitch gradient is studied by the finite element method. It is observed that the transmission spectrum can be tailored by incorporating the defects of pitch jump and phase jump in the cholesteric helix. The device is polarization sensitive and exhibits passive anisotropic transmission analogous to the electronic diode. For incident circularly polarized light with the same handedness as the cholesterics, the introduction of the defects in the helical structure leads to the exhibition of unidirectional multiple-band-pass characteristics inside the photonic band gap region. Due to the asymmetrical local resonator cavity, a notable enhancement in the transmission contrast can be realized. Some critical parameters for the non-reciprocal transmission behavior are demonstrated theoretically: the apodization function, the thickness of the double composite film, and the twist angle. In addition, the defect wavelengths in the transmission spectrum can be tuned linearly by adjusting the amount of the phase jump. Equipped with a different phase jump according to the linear behavior, it is easy for the optical diode to control the unidirectional transmission channels..

Keywords

Optical diode, Photonic crystal, Cholesteric liquid crystal, Defect mode, Apodization.

Submitted at: March 5, 2007
Accepted at: Aug. 18, 2007

Citation

JIUN-YEU CHEN, Optical diode based on unidirectional transmission of defect modes in cholesteric liquid crystals: A simulation study, Journal of Optoelectronics and Advanced Materials Vol. 9, Iss. 8, pp. 2437-2444 (2007)