Ultra-small optical cavity array capable of controlling the 2-D mode profile in nanometer scale

Abstract

This thesis reports studies on controlling the two-dimensional mode profile of the optical mode focused on the cavity in the nanometer scale. A metal-insulator-metal(MIM) structure is adopted to strongly control the electric field distribution. Using the FDTD simulation, it was confirmed that the electric field distribution of the optical mode can be controlled by adjusting the width and gap of the metal layers since the electric field of the optical mode is mostly confined in the region between the metal layers. In order to demonstrate this experimentally, we fabricated an optical cavity which can control the width and gap of the metal layers independently in nanometer scale using multi-dimensional deposition process. The presence of the optical modes in the fabricated structures were analyzed using the FDTD simulation and experimentally confirmed through the tapered fiber coupling measurement and the transmission spectrum analysis. Also, it was confirmed that the electric field distribution is controlled by modifying the MIM structure by measuring the change of the second harmonic generation (SHG) signal. Subsequently, using the fact that the electric field distribution can be controlled at the molecular regime, it has been shown that nanometer-sized proteins can be detected with high sensitivity.