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

摘要

Synthesized micro- and nanotubes composed of transition metaldichalcogenides (TMDCs) such as MoS_2 are promising for many applicationsin nanophotonics because they combine the abilities to emit strong excitonluminescence and to act as whispering gallery microcavities even at roomtemperature. In addition to tubes in the form of hollow cylinders, there is aninsufficiently studied class of twisted tubes, the flattened cross-section ofwhich rotates along the tube axis. As shown by theoretical analysis, in suchnanotubes the interaction of electromagnetic waves excited at the oppositesides of the cross-section can cause splitting of the whispering gallery modes.By studying micro-photoluminescence spectra measured along individualMoS_2 tubes, it has been established that the splitting value, which controlsthe energies of the split modes, depends exponentially on the aspect ratio ofthe cross-section, which varies in “breathing” tubes, while the relativeintensity of the modes in a pair is determined by the angle of rotation of thecross-section. These results open up the possibility of creating multifunctionaltubular TMDC nanodevices that provide resonant amplification ofself-emitting light at adjustable frequencies.