Twisted Nanotubes of Transition Metal Dichalcogenides with Split Optical Modes for Tunable Radiated Light Resonators

TL;DR

This paper investigates twisted MoS2 nanotubes, revealing how their split optical modes depend on geometric factors, enabling tunable nanophotonic resonators with potential for multifunctional light-emitting devices.

Contribution

It introduces the study of twisted TMDC nanotubes with split whispering gallery modes and demonstrates how their optical properties depend on geometric parameters, offering new design possibilities.

Findings

Splitting of whispering gallery modes depends exponentially on the aspect ratio.

Mode intensity is influenced by the rotation angle of the cross section.

Tunable resonant amplification of light can be achieved in these nanotubes.

Abstract

Synthesized micro- and nanotubes composed of transition metal dichalcogenides (TMDCs) such as MoS$_2$ are promising for many applications in nanophotonics, because they combine the abilities to emit strong exciton luminescence and to act as whispering gallery microcavities even at room temperature. In addition to tubes in the form of hollow cylinders, there is an insufficiently-studied class of twisted tubes, the flattened cross section of which rotates along the tube axis. As shown by theoretical analysis, in such nanotubes the interaction of electromagnetic waves excited at opposite sides of the cross section can cause splitting of the whispering gallery modes. By studying micro-photoluminescence spectra measured along individual MoS$_2$ tubes, it has been established that the splitting value, which controls the energies of the split modes, depends exponentially on the aspect ratio of the cross section, which varies in "breathing" tubes, while the relative intensity of the modes in a pair is determined by the angle of rotation of the cross section. These results open up the possibility of creating multifunctional tubular TMDC nanodevices that provide resonant amplification of self-emitting light at adjustable frequencies.