Sub-30 fs all-optical switching based on dielectric photonics

G. GRINBLAT; R. BERTÉ; M. P. NIELSEN; Y. LI; P. DICHTL; R. F. OULTON; S. A. MAIER

Workshop; Discussion on Nano and Mesoscopic Optics; 2019

The realisation of compact and efficient all-optical information processing devices at the nanometre scale has attracted great attention within the nanophotonics community in recent years, as they are expected to overcome the intrinsic speed and heat dissipation limitations of conventional electronics. In particular, nonlinear optical effects are predicted to give rise to the fastest performances, as they can produce response times in the femtosecond range [1].Benefiting from large intrinsic nonlinearities and high field confinement abilities, nanostructured high refractive index dielectrics are crucial for efficient ultrafast nonlinear processes at subwavelength volumes [2]. In this work, we implement a novel pump-probe method using 7 fs pulses to investigate the ultrafast dynamics of single Si nanodisks fabricated through e-beam lithography, covered with a thin 30-nm thick layer of Au to enhance sample reflectivity and thermal dissipation. We demonstrate that the nanoantenna can generate positive and negative sub-20 fs reflectivity modulations of ∼0.3% at resonance, in the visible to near-infrared spectral range [3]. Recent measurements on GaP showing the possibility to enhance this response will also be discussed. The results suggest that the nonlinear optical Kerr effect and two-photon absorption are the responsible mechanisms for the observed all-optical switching phenomena.References[1] S. V. Makarov et al. Laser Photonics Rev. 11, 1700108 (2017). [2] G. Grinblat et al. ACS Nano 11, 953-960 (2017). [3] G. Grinblat et al. Nano Lett. 18, 7896?7900 (2018).