Nonlinear exciton-Mie coupling in transition metal dichalcogenides nanoresonators

TL;DR

This paper demonstrates the fabrication of MoS2 nanodisks supporting magnetic dipole Mie resonances, leading to enhanced second-harmonic generation due to resonant overlap, advancing nonlinear optical applications of TMDC nanostructures.

Contribution

It introduces a fabrication method for MoS2 nanodisks with magnetic Mie resonances and shows enhanced nonlinear optical response through resonance tuning.

Findings

Magnetic dipole Mie resonances observed in MoS2 nanodisks.

Resonance tuning enhances second-harmonic generation.

Crystallinity retained after fabrication.

Abstract

Molybdenum disulfide (MoS2) is a layered material of transition metal dichalcogenides (TMDCs) with a high refractive index in the visible and infrared spectral range. Therefore, by constructing MoS2 into dielectric nanoresonators, one can generate highly confined electromagnetic Mie-type modes. In this work, we applied lithography and etching techniques to single crystal MoS2 flakes to fabricate nanodisks that support magnetic dipole Mie resonances in near infrared spectral range. The nanodisks were studied by second-harmonic generation (SHG) rotational anisotropy revealing the retention of crystallinity and the orientation of the crystallographic axes of the single disk structure after fabrication. Magnetic dipole resonances manifest as resonant intensity enhancement in SHG spectra. Tuning Mie resonances by selecting the geometrical size of MoS2 nanodisks, we demonstrated strongly enhanced SHG due to the overlap of the optical resonance at the fundamental wavelength with the C-exciton resonance at the second-harmonic wavelength.