New publication: Second-order optical nonlinearity in TMD nanotriangles (Phys. Rev. B Letter)

Former group member Dr. Farhad Karimi, PhD student Sina Soleimanikahnoj, and Prof. Irena Knezevic coauthored the recent publication “Tunable plasmon-enhanced second-order optical nonlinearity in transition-metal-dichalcogenide nanotriangles,” Phys. Rev. B (Letter103, L161401 (2021). [Publisher’s link] [Preprint on arXiv]

Illustration of a TMD nanotriangle with second-harmonic response

Abstract: The development of nanomaterials with a large nonlinear susceptibility is essential for nonlinear nanophotonics. We show that transition metal dichalcogenide (TMD) nanotriangles have a large effective second-order susceptibility at midinfrared to near-infrared frequencies owing to their broken centrosymmetry. χ(2) is calculated within the density-matrix formalism that accounts for dissipation and screening. χ(2) peaks in the vicinity of both two-photon resonances (specified by the geometry) and plasmon resonances (tunable via the carrier density). Aligning the resonances yields the values of χ(2) as high as 10−6 m/V. These findings underscore the potential of TMD nanotriangles for nonlinear nanophotonics, particularly second-harmonic generation.