4 research outputs found
Twisted Nanotubes of Transition Metal Dichalcogenides with Split Optical Modes for Tunable Radiated Light Resonators
Synthesized micro- and nanotubes composed of transition metal dichalcogenides
(TMDCs) such as MoS 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 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
Boron Nitride Thin Films with Anisotropic Optical Properties from Microscale Particle Density Distributions
Unusual optical anisotropy was experimentally observed in hexagonal boron nitride thin films produced from bulk boron nitride via ultrasonication. Both the linear and circular polarisation demonstrated a well-defined single axis of anisotropy over a large sample area. To understand this phenomenon, we employed statistical analysis of optical microscopy images and atomic force microscopy to reveal an ordered particle density distribution at the microscopic level corresponding to the optical axis observed in the polarisation data. The direction of the observed ordering matched the axis of anisotropy. Hence, we attribute the measured optical anisotropy of the thin films to microscopic variations in the particle density distribution
Boron nitride thin films with anisotropic optical properties from microscale particle density distributions
Abstract
Unusual optical anisotropy was experimentally observed in hexagonal boron nitride thin films produced from bulk boron nitride via ultrasonication. Both the linear and circular polarisation demonstrated a well-defined single axis of anisotropy over a large sample area. To understand this phenomenon, we employed statistical analysis of optical microscopy images and atomic force microscopy to reveal an ordered particle density distribution at the microscopic level corresponding to the optical axis observed in the polarisation data. The direction of the observed ordering matched the axis of anisotropy. Hence, we attribute the measured optical anisotropy of the thin films to microscopic variations in the particle density distribution