One-Dimensional Quasi-Plasmonic Crystal Containing a Liquid-Crystal Layer

• Main Authors: Tsai, Pei-Hsiang, 蔡沛享
• Other Authors: Lee, Wei
• Format: Others
• Language: zh-TW
• Published: 2015
• Online Access: http://ndltd.ncl.edu.tw/handle/59809919846580757205

碩士 === 國立交通大學 === 照明與能源光電研究所 === 103 === Surface modes are a fascinating type of modes that are confined at a single boundary between two different media. Due to their intrinsic properties and extrinsic effects as well as their prospects for important applications, continuously renewed interest in surface modes has been sparked in recent years. In this study, we propose an electrically tunable and spectral absorption-frequency-selective device on the basis of one-dimensional quasi-plasmonic crystals containing a liquid-crystal (LC) defect layer. The structure is composed of two distinct metallo (M)-dielectric (D) multilayers sandwiching a 4.65-m-thick and planar-alignment nematic LC (HDN) layer. While one multiplayer has a (DMD)1 configuration, the other is configured as (DMD)5, where each transparent dielectric layer is Al2O3 of eighth wavelength in thickness and each metallic layer is quarter-wavelength-thick Ag. Sharp reflection peaks resembling a comb are present in the visible and near-infrared ranges in the spectrum which are originated from cavity modes and surface modes that are tentatively identified to be Dyakonov surface modes. The wavelengths of the reflection and absorption peaks can be tuned by applying an electric field to the LC defect layer, yielding a blueshift of up to ~70 nm in simulation and 35 nm in experiment as the applied voltage increases along with the spectacular phenomenon-anticrossing. This research is expected to bring about prospective applications in resonant cavities, optical filters, and plasmon–resonance sensing for physical, chemical and biological agents.