Superior Nonlinear Optical Response in Non-Centrosymmetric Stacking Edge-Rich Spiral MoTe2 Nanopyramids

Transition metal dichalcogenides (TMDs) are of great promise for various nonlinear optical (NLO) applications due to their unique electronic and optoelectronic properties, such as tunable optical bandgap, strong spin-orbit coupling, and exciton effects. However, the desired NLO performances of regular 2H-TMDs are usually restricted by their limited absorption at atomic thickness. With this regard, a structurally novel spiral MoTe2 (s-MoTe2) nanopyramids is reported with unique and superior NLO response, enabled by their broken inversion symmetry, weak interlayer coupling, exciton resonance, and strong light-matter interaction from the edge-rich 3R-like quasi-multilayer structure. The excellent NLO response over a wide spectral range from the near-infrared to visible region is demonstrated, where second- and third-order NLO responses have been simultaneously observed. Moreover, the second-order nonlinear susceptibility of s-MoTe2 is estimated to be around 1-2 order(s) of magnitude larger than those of most reported TMDs. The demonstration of a superior NLO response in such s-MoTe2 not only paves a new way for designing the best NLO TMD structures, but also greatly prompts their practical applications in micro-nano NLO devices on chips in future.

Automated summary

A structurally novel spiral MoTe2 nanopyramids with unique and superior nonlinear optical (NLO) response has been reported. This nanostructure exhibits excellent second- and third-order NLO responses over a wide spectral range. The second-order nonlinear susceptibility of s-MoTe2 is estimated to be 1-2 orders of magnitude larger than most reported TMDs. This study not only provides a new way for designing the best NLO TMD structures, but also greatly promotes their practical applications in micro-nano NLO devices on chips in the future.