Research (Jan 2020)

Structuring Nonlinear Wavefront Emitted from Monolayer Transition-Metal Dichalcogenides

  • Xuanmiao Hong,
  • Guangwei Hu,
  • Wenchao Zhao,
  • Kai Wang,
  • Shang Sun,
  • Rui Zhu,
  • Jing Wu,
  • Weiwei Liu,
  • Kian Ping Loh,
  • Andrew Thye Shen Wee,
  • Bing Wang,
  • Andrea Alù,
  • Cheng-Wei Qiu,
  • Peixiang Lu

DOI
https://doi.org/10.34133/2020/9085782
Journal volume & issue
Vol. 2020

Abstract

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The growing demand for tailored nonlinearity calls for a structure with unusual phase discontinuity that allows the realization of nonlinear optical chirality, holographic imaging, and nonlinear wavefront control. Transition-metal dichalcogenide (TMDC) monolayers offer giant optical nonlinearity within a few-angstrom thickness, but limitations in optical absorption and domain size impose restriction on wavefront control of nonlinear emissions using classical light sources. In contrast, noble metal-based plasmonic nanosieves support giant field enhancements and precise nonlinear phase control, with hundred-nanometer pixel-level resolution; however, they suffer from intrinsically weak nonlinear susceptibility. Here, we report a multifunctional nonlinear interface by integrating TMDC monolayers with plasmonic nanosieves, yielding drastically different nonlinear functionalities that cannot be accessed by either constituent. Such a hybrid nonlinear interface allows second-harmonic (SH) orbital angular momentum (OAM) generation, beam steering, versatile polarization control, and holograms, with an effective SH nonlinearity χ2 of ~25 nm/V. This designer platform synergizes the TMDC monolayer and plasmonic nanosieves to empower tunable geometric phases and large field enhancement, paving the way toward multifunctional and ultracompact nonlinear optical devices.