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

Abstract 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.