Whispering-gallery modes and light emission from a Si-nanocrystal-based single microdisk resonator

TL;DR

This paper demonstrates visible light emission from Si-nanocrystal microdisk resonators, revealing whispering-gallery modes with high quality factors and mode linewidth modifications influenced by pump power, advancing integrated photonics.

Contribution

It reports the first observation of whispering-gallery modes in Si-nanocrystal microdisks with high Q-factors and analyzes mode linewidth changes due to pump power effects.

Findings

High quality factors up to 2800 achieved.

Mode linewidth varies by a factor of 13 with pump power.

Thinner disks support only TE-like modes, enabling mode filtering.

Abstract

We report on visible light emission from Si-nanocrystal based optically active microdisk resonators. The room temperature photoluminescence (PL) from single microdisks shows the characteristic modal structure of whispering-gallery modes. The emission is both TE and TM-polarized in 300 nm thick microdisks, while thinner ones (135 nm) support only TE-like modes. Thinner disks have the advantage to filter out higher order radial mode families, allowing for measuring only the most intense first order modal structure. We reveal subnanometer linewidths and corresponding quality factors as high as 2800, limited by the spectral resolution of the experimental setup. Moreover,we observe a modification of mode linewidth by a factor 13 as a function of pump power. The origin of this effect is attributed to an excited carrier absorption loss mechanism.