Abstract
AbstractDiamond has attracted great interest as an appealing material for various applications ranging from classical to quantum optics. To date, Raman lasers, single photon sources, quantum sensing and quantum communication have been demonstrated with integrated diamond devices. However, studies of the nonlinear optical properties of diamond have been limited, especially at the nanoscale. Here, a metasurface consisting of plasmonic nanogap cavities is used to enhance both χ(2) and χ(3) nonlinear optical processes in a wedge-shaped diamond slab with a thickness down to 12 nm. Multiple nonlinear processes were enhanced simultaneously due to the relaxation of phase-matching conditions in subwavelength plasmonic structures by matching two excitation wavelengths with the fundamental and second-order modes of the nanogap cavities. Specifically, third-harmonic generation (THG) and second-harmonic generation (SHG) are both enhanced 1.6 × 107-fold, while four-wave mixing is enhanced 3.0 × 105-fold compared to diamond without the metasurface. Even though diamond lacks a bulk χ(2) due to centrosymmetry, the observed SHG arises from the surface χ(2) of the diamond slab and is enhanced by the metasurface elements. The efficient, deeply subwavelength diamond frequency converter demonstrated in this work suggests an approach for conversion of color center emission to telecom wavelengths directly in diamond.
Highlights
Diamond has attracted great interest as an appealing material for various applications ranging from classical to quantum optics
Third-harmonic generation (THG) and second-harmonic generation (SHG) are both enhanced 1.6 × 107-fold, while four-wave mixing is enhanced 3.0 × 105-fold compared to diamond without the metasurface
When the excitation wavelength overlaps with the cavity resonance, both third-harmonic generation (THG) and secondharmonic generation (SHG) are dramatically enhanced compared to a thin diamond slab reference
Summary
Diamond has attracted great interest as an appealing material for various applications ranging from classical to quantum optics. A metasurface consisting of plasmonic nanogap cavities is used to enhance both χ(2) and χ(3) nonlinear optical processes in a wedge-shaped diamond slab with a thickness down to 12 nm. Multiple nonlinear processes were enhanced simultaneously due to the relaxation of phase-matching conditions in subwavelength plasmonic structures by matching two excitation wavelengths with the fundamental and second-order modes of the nanogap cavities.
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