Plasmonic whispering-gallery modes in a semiconductor-based hybrid structure
Chien-Ju Lee1*, Han Yeh1, Yen-Chun Chen1, Chun-Yuan Wang2, Shangir Gwo2, Jer-Shing Huang3, Wen-Hao Chang1
1Department of Electrophysics, National Chiao Tung University, Hsinchu 30010, Taiwan
2Department of Physics, National Tsing Hua University, Hsinchu 30013, Taiwan
3Department of Chemistry, National Tsing Hua University, Hsinchu 30013, Taiwan
* presenting author:李建儒,
We demonstrate a simple method to fabricate plasmonic cavities based on a hybrid semiconductor-insulator-metal structure, which can support plasmonic whispering-gallery modes (WGM) in the insulator layer. The hybrid structure consists of a semiconductor microdisk with embedded quantum dots on top of a single crystalline gold flake with a nanometers-thick dielectric gap in between. Microdisks with different diameters and dielectric layers with different thicknesses were fabricated and characterized by photoluminescence measurements. The observed plasmonic modes have been identified by comparing the measured spectra to finite-element simulations. Furthermore, the simulation suggests that, by varying the dielectric layer thickness, photonic resonant modes confined in the semiconductor layer can be strongly coupled to the plasmonic resonant modes confined in the dielectric gap. This kind of photon-plasmon polariton will be formed when the plasmonic mode and photonic mode exhibit an anti-crossing character.

Keywords: surface plasmon, microcavities