Tunable Surface Plasmon Resonances Based on Chromium Disk Array Containing Liquid Crystals

The tunable surface plasmon resonances of an indium tin oxide (ITO) cell embedded with a chromium disk array and liquid crystals (LCs) have been investigated. The chromium disk array with a diameter of 300 nm and a period of 600 nm was fabricated on one ITO film and the LCs were infiltrated into the ITO cell. The effective refractive indices of the sandwiched LCs may be tuned from 1.51 to 1.73 by applying external electrical fields across the two ITO films. The optical transmission spectra reveal two resonances that may be modulated from 482 to 575 nm and from 670 to 723 nm within the range of tuning. In addition, the tunable surface plasmon resonances illustrate hysteresis behaviors. These results are identified to be associated with the alignment of LCs that is modulated by the electrical fields.