Ultrafast sub-30-fs all-optical switching based on gallium phosphide

GRINBLAT, GUSTAVO; LI, YI; NIELSEN, MICHAEL P.; OULTON, RUPERT F.; DICHTL, PAUL; MAIER, STEFAN A.

Science Advances

American Association for the Advancement of Science

Año: 2019 vol. 5

Gallium phosphide (GaP) is one of the few available materials with strong optical nonlinearity and negligible losses in the visible (l > 450 nm) and near-infrared regime. In this work, we demonstrate that a GaP film can generate sub?30-fs (full width at half maximum) transmission modulation of up to ~70% in the 600- to 1000-nm wavelength range. Nonlinear simulations using parameters measured by the Z-scan approach indicate that the transmission modulation arises from the optical Kerr effect and two-photon absorption. Because of the absence of linear absorption, no slower free-carrier contribution is detected. These findings place GaP as a promising ultrafast material for all-optical switching at modulation speeds of up to 20 THz.