Enhanced second-harmonic generation from resonant GaAs gratings

Abstract

We study second harmonic generation in nonlinear, GaAs gratings. We find large enhancement of conversion efficiency when the pump field excites the guided mode resonances of the grating. Under these circumstances the spectrum near the pump wavelength displays sharp resonances characterized by dramatic enhancements of local fields and favorable conditions for second harmonic generation, even in regimes of strong linear absorption at the harmonic wavelength. In particular, in a GaAs grating pumped at 1064nm, we predict second harmonic conversion efficiencies approximately five orders of magnitude larger than conversion rates achievable in either bulk or etalon structures of the same material.

Second Harmonic Generation Circular Dichroism from Self‐Ordered Hybrid Plasmonic–Photonic Nanosurfaces

“…[ 16,21 ] Indeed it is well known that the SHG process is extremely sensitive to interface details and for this reason optical SHG techniques have been used to image ferroelectric [ 27 ] and ferromagnetic [ 28 ] domains as well as to determine the chirality [ 16 ] of nanostructures or organic molecules and biological materials. Recently, a giant enhancement of SHG has been reported both in three dimensional metal nanostructures [ 18,19,24 ] and in sub-wavelength resonant waveguide gratings [ 30,31 ] composed by a dielectric sub-wavelength grating covered by a thin coating of a high refractive index material acting as a lossy waveguide. Recently, a giant enhancement of SHG has been reported both in three dimensional metal nanostructures [ 18,19,24 ] and in sub-wavelength resonant waveguide gratings [ 30,31 ] composed by a dielectric sub-wavelength grating covered by a thin coating of a high refractive index material acting as a lossy waveguide.…”

“…Recently, a giant enhancement of SHG has been reported both in three dimensional metal nanostructures [ 18,19,24 ] and in sub-wavelength resonant waveguide gratings [ 30,31 ] composed by a dielectric sub-wavelength grating covered by a thin coating of a high refractive index material acting as a lossy waveguide. [ 31 ] By taking advantage of this effect, enhancement in the SHG effi ciency by 4 orders of magnitude has been reported. [ 31 ] By taking advantage of this effect, enhancement in the SHG effi ciency by 4 orders of magnitude has been reported.…”

“…[ 29 ] Thus, the optimization of the SHG emission from nano-patterned surfaces can be interesting for the production of substrates enabling enhanced nonlinear SHG microscopy. Recently, a giant enhancement of SHG has been reported both in three dimensional metal nanostructures [ 18,19,24 ] and in sub-wavelength resonant waveguide gratings [ 30,31 ] composed by a dielectric sub-wavelength grating covered by a thin coating of a high refractive index material acting as a lossy waveguide. [ 32 ] The mechanisms at the basis of the SHG enhancement are completely different in the two schemes: in the case of metal nanostructures, as discussed above, the second harmonic response is driven by the strong fi eld localization as a consequence of the excitation of localized surface plasmon polaritons; in contrast, in resonant waveguide gratings, at the resonant frequency, the fi elds diffracted out of the waveguide mode interfere with the transmitted and refl ected fi elds in such a way that the fi eld in the waveguide mode can be signifi cantly localized.…”

Efficient second-harmonic generation in silicon nitride resonant waveguide gratings

“…Enhanced SHG in resonant nanostructures such as photonic crystals [5,6], gratings [7][8][9], or nanowaveguides [10,11] has been widely studied in the last decade. More recently, metal nanostructures have received increasing attention, where enhanced SHG is achieved through the strong field localization associated with the excitation of surface plasmon resonances [12][13][14].…”

Second harmonic generation (SHG) from resonant GaAs gratings

“…The pump field incident at 10° on the grating is TE polarized and the generated SH is also TE-polarized. This is a typical experimental configuration for SHG From[3]) a) Sketch of the pump signal incident at 9=10° on the grating. The grating is subwavelength for the pump field (1064nm), while the diffracted SHG is distributed on the zeroth order at 90•sH=IO o and the first order at 9_I.SH�63° in the case of a grating with period P=500nm.…”