Doubly-Resonant Enhancement of Second Harmonic Generation from a WS2 Nanomesh Polymorph with a Modified Energy Landscape

Alexander W.A. Murphy, Zichen Liu, Andrey V. Gorbach, Adelina Ilie, Ventsislav K. Valev

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9 Citations (SciVal)


Although transition metal dichalcogenides (TMDs, e.g., WS2, WSe2, MoS2, MoSe2) have emerged as highly promising 2D materials for nonlinear optics, they are limited by intrinsically small light-matter interaction length and (typically) flat-lying geometries. The first hyperspectral multiphoton analysis of a tridimensional webbed network of densely-packed stacks (of 1–5 layers) of twisted and/or fused 2D nanosheets of WS2, referred to as “nanomesh”, is presented here. The optical second harmonic generation (SHG) is mapped across the three characteristic spectral features (A, B, and C) and two-photon luminescence and third harmonic generation signatures are established. Compared to flat-lying WS2 layers, the nanomesh is highly efficient, broadband, and robust against degradation (with main enhancement originating from the C feature, spreading from 850 to 1100 nm), and scalable in terms of growth. The origin of these spectral differences is assigned to hotspots, whose location changes depending on the wavelength of illumination. The main SHG enhancements result from double resonances in an energy landscape modified by in-built defects (e.g., vacancies and their passivated variants, or grain boundaries) that induce intra-bandgap energy levels. These characteristics establish the nanomesh as a prime candidate for integration into quantum optical technologies, such as miniaturized devices on chip.

Original languageEnglish
Article number2100117
JournalLaser and Photonics Reviews
Issue number6
Early online date10 May 2021
Publication statusPublished - 10 Jun 2021

Bibliographical note

Funding Information:
The authors thank Prof William Wadsworth for useful discussions. V.K.V. acknowledges support from the Royal Society through the University Research Fellowships. The authors acknowledge Royal Society grants PEF1∖170015 and RGF∖EA∖180228, as well as STFC grant ST/R005842/1 and EPSRC grants EP/L015544/1 and EP/T001046/1. Z.L. acknowledges a studentship from the University of Bath. The authors gratefully acknowledge the Material and Chemical Characterisation Facility (MC²) at University of Bath ( ) and especially Dr. Michael Zachariadis and Dr. Philip Fletcher for technical support and assistance in this work.


  • 2D materials
  • multiphoton spectroscopy
  • nonlinear optics
  • second harmonic generation
  • transition metal dichalcogenides

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Atomic and Molecular Physics, and Optics
  • Condensed Matter Physics


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