Nanocavity induced by atomically thin transition metal dichalcogenide in photonic crystal waveguide

Abstract

Photonic crystal (PhC) cavities can be formed by depositing materials onto PhC waveguides post-fabrication to modulate the local refractive index. Previous studies suggested that ultrahigh Q-factor PhC cavities could be formed with a small local refractive index modulation of ~0.1% [1, 2]. However, experimental attempts to create such cavities by depositing poly(methyl methacrylate) (PMMA) onto GaAs PhC waveguides were unable to achieve ultrahigh Q cavities because of the thick polymer layer [3]. Another approach of placing nanowires along the PhC waveguide to induce the formation of nanocavities have also been reported [4, 5]. Alternatively, 2D materials with their atomically thin nature represent a novel platform to realize the small refractive index modulation to induce high Q nanocavity in a PhC waveguide. In this work, we report the observation of high Q-factor nanocavities formed by placing atomically thin transition metal dichalcogenide (TMDC) flakes onto PhC waveguides.