Mode matching in multiresonant plasmonic nanoantennas for enhanced second harmonic generation

Abstract

ABSTRACT:Boosting nonlinear frequency conversion in extremely confined volumes remains a key challenge in nano-optics, nanomedicine, photocatalysis, and background-free biosensing. To this aim, field enhancements in plasmonic nanostructures are often exploited to effectively compensate for the lack of phase-matching at the nanoscale. Second harmonic generation (SHG) is, however, strongly quenched by the high degree of symmetry in plasmonic materials at the atomic scale and in nanoantenna designs.Here, we devise a plasmonic nanoantenna lacking axial symmetry, which exhibits spatial and frequency mode overlap at both the excitation and the SHG wavelengths. The effective combination of these features in a single device allows obtaining unprecedented SHG conversion efficiency. Our results shed new light on the optimization of SHG at the nanoscale, paving the way to new classes of nanoscale coherent light sources and molecular sensing devices based on nonlinear plasmonic platforms.

Resonantly Enhanced Second-Harmonic Generation Using III–V Semiconductor All-Dielectric Metasurfaces

“…Figure 3 This increase is even more impressive, considering that the pump beam was much more tightly focused in Ref. 9, while the nonlinear coefficient (which is defined solely in terms of powers) scales inversely with the spot size. Furthermore, a higher NA objective (1.35) was used in Ref.…”

“…The SHG power exhibits peaks in the vicinity of the magnetic (~1020 nm) and electric (~890 nm) dipole resonances due the electromagnetic field enhancements that occur at these resonances. Indeed, electromagnetic simulations described below show that at these resonances the field 9 intensities are ~30 times stronger than the incident pump intensity. The SH signal obtained when the pump coincides with the magnetic and electric dipole resonances are more than 3 and 1 orders of magnitude higher than the signal obtained when pumping at off-resonant wavelengths.…”

“…Furthermore, a higher NA objective (1.35) was used in Ref. 9, as compared to the NA =0.42 objective used in the current work which allowed collection of a larger portion of the radiated SHG power (some of which is emitted in diffraction lobes).…”

Enhanced second-harmonic generation from magnetic resonance in AlGaAs nanoantennas

“…Second harmonic generation in plasmonic nanostructures has been deeply investigated in recent years, often enhanced by matching localised surface plasmon resonance (LSPR) either with the excitation or the emission wavelength [20][21][22]. Furthermore, SHG from metaldielectric-metal metasurfaces has been studied [23].…”

Resonant plasmonic nanoparticles for multicolor second harmonic imaging

“…13,14 Second harmonic from RPNPs has been recently measured, [15][16][17][18] and different methods to further enhance this nonlinear effect by engineering the RPNPs have been proposed. [19][20][21][22][23] Interestingly, in a recent work, 24 we showed that the SH spectrum generated by RPNPs interacting with sufficiently broadband laser pulses depends on both the laser spectrum and the LSPR. This gives the unique possibility of distinguishing two different RPNPs, characterized by different LSPRs, based on their SH spectra.…”