Abstract
Two-dimensional (2D) layered materials, with large second-order nonlinear susceptibility, are currently growing as an ideal candidate for fulfilling tunable nanoscale coherent light through the second-order nonlinear optical parametric processes. However, the atomic thickness of 2D layered materials leads to poor field confinement and weak light-matter interaction at nanoscale, resulting in low nonlinear conversion efficiency. Here, hybrid three-dimensional (3D) spiral WSe2 plasmonic structures are fabricated for highly efficient second harmonic generation (SHG) and sum-frequency generation (SFG) based on the enhanced light-matter interaction in hybrid plasmonic structures. The 3D spiral WSe2, with AA lattice stacking, exhibits efficient SH radiation due to the constructive interference of nonlinear polarization between the neighboring atomic layers. Thus, extremely high external SHG conversion efficiency (about 2.437×10−5) is achieved. Moreover, the ease of phase-matching condition combined with the enhanced light-matter interaction in hybrid plasmonic structure brings about efficient SHG and SFG simultaneously. These results would provide enlightenment for the construction of typical structures for efficient nonlinear processes.
Highlights
Broadband tunable coherent light sources with smallfootprint and low power consumption have attracted great attention because of their potential applications ranging from high-throughput sensing to on-chip photonic communication [1,2,3,4]
Transition metal dichalcogenides (TMDC), with broken inversion symmetry structure in the monolayer limit which brings about nonvanishing second-order nonlinear susceptibility [7,8,9], have been widely applied for obtaining Second harmonic generation (SHG) at nanoscale size
Due to the diffraction limit of light, the small sizes of TMDC lead to poor field confinement, which results in low nonlinear optical conversion efficiency
Summary
Broadband tunable coherent light sources with smallfootprint and low power consumption have attracted great attention because of their potential applications ranging from high-throughput sensing to on-chip photonic communication [1,2,3,4]. Second harmonic generation (SHG) and sumfrequency generation (SFG) [5, 6], which are based on the second-order nonlinear optical parametric processes, are emerging as ideal alternatives to nanoscale lasers due to their wide wavelength modulation range. Transition metal dichalcogenides (TMDC), with broken inversion symmetry structure in the monolayer limit which brings about nonvanishing second-order nonlinear susceptibility [7,8,9], have been widely applied for obtaining SHG at nanoscale size. Due to the diffraction limit of light, the small sizes (at subwavelength scale) of TMDC lead to poor field confinement, which results in low nonlinear optical conversion efficiency. Thicker TMDC nanostructures with effective subwavelength electromagnetic field confinement are needed for highly efficient nonlinear optical applications
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