Browsing by Author "de Ceglia, D."
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Item Enhanced nonlinear optics in resonant GaAs gratings: harmonic generation and optical bistability(SPIE, 2011-09-09) de Ceglia, D.; D'Aguanno, G.; Mattiucci, N.; Vincenti, M. A.; Bloemer, M. J.; Scalora, M.We present a study on nonlinear optical processes in GaAs gratings, made by perforating a single layer of GaAs with very narrow slits. Large enhancement of conversion efficiency, for both second and third harmonic generation, is predicted when a TE-polarized pump field excites the guided mode resonances of the grating. At the onset of these modes the spectrum near the pump wavelength shows abrupt changes of linear transmission and reflection that follow a typical Fano-like shape. Under these circumstances, the grating provides dramatic enhancement of local fields and fosters favorable conditions for harmonic generation processes, even in regimes of strong linear absorption at the harmonic wavelengths. In a GaAs grating pumped at 1064nm, we predict second (532nm) and third (354nm) harmonic conversion efficiencies several orders of magnitude larger than conversion rates achievable in either bulk or etalon structures made of the same material. These efficiencies are not influenced by linear absorption, and they are unrelated to grating thickness. We discuss the influence of self-phase modulation on the harmonic generation conversion efficiencies. Finally, we also analyze self phase modulation effects on resonant gratings tuning the input signal at guided mode resonances, demonstrating the possibility of triggering optical bistability at relatively low switching intensities.Item Enhanced second-harmonic generation from resonant GaAs gratings(OSA Publishing, 2011) de Ceglia, D.; D’Aguanno, G.; Mattiucci, N.; Vincenti, M. A.; Scalora, M.We theoretically 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 1064 nm, we predict second-harmonic conversion efficiencies approximately 5 orders of magnitude larger than conversion rates achievable in either bulk or etalon structures of the same material.Item Experimental demonstration of plasmonic Brewster angle extraordinary transmission through extreme subwavelength slit arrays in the microwave(American Physical Society, 2012-05-15) Aközbek, N.; Mattiucci, N.; de Ceglia, D.; Trimm, R.; Alù, A.; D’Aguanno, G.; Vincenti, M. A.; Scalora, M.; Bloemer, M. J.We experimentally demonstrate the existence of a Brewster-like broadband extraordinary optical transmission band, in a very thick metal plate with an array of slits as narrow as λ/750 in the 8- to 40-GHz regime, by measuring the transmission from normal incidence to near grazing angles and mapping out the entire angular transmission spectrum. In the case of very narrow slits, an order of magnitude larger transmission is obtained at the Brewster angle when compared to the normal-incidence Fabry-Pérot resonance transmission peaks. Full-wave numerical simulations are in excellent agreement with the measurements, paving the way for the observation of this phenomenon in the optical regime.Item Second harmonic generation (SHG) from resonant GaAs gratings(OSA Publishing, 2011-05-22) de Ceglia, D.; D’Aguanno, G.; Mattiucci, N.; Vincenti, M.A.; Scalora, M.We study SHG in nonlinear (NL), GaAs gratings. We find large enhancement of conversion efficiency when the pump field excites the guided mode resonances (GMRs) [1] 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 SH wavelength thanks to the phase-locked (PL) component of the SH [2]. In particular, in a GaAs grating pumped at 1064nm, we predict SH conversion efficiencies approximately five orders of magnitude larger than conversion rates achievable in either bulk or etalon structures of the same materials [3]. In Fig.1a) we sketch the geometry under consideration and in Fig.1b) we calculate the forward SH conversion efficiency 𝜂=𝑃ₛₕ/𝑃²𝐹𝐹 as function of the grating thickness W and compare it with the conversion efficiency of a bulk GaAs and with the conversion efficiency of an etalon GaAs placed in vacuo. The pump field incident at 100 on the grating is TE-polarized and the generated SH is also TE-polarized. This is a typical experimental configuration for SHG in GaAs [2].