Hot electron dynamics in ultrafast multilayer epsilon-near-zero metamaterials

Abstract

Realizing remarkable tunability in optical properties without sacrificing\nspeed is critical to obtain all optical ultrafast devices. In this work, we\ninvestigate the ultrafast temporal behavior of optically tunable\nepsilon-near-zero (ENZ) metamaterials, operating in the visible spectral range.\nTo perform this the ultrafast dynamics of the hot electrons is acquired by\nfemtosecond pump-probe spectroscopy and studied based on two-temperature model\n(2TM). We show that pumping with femtosecond pulses changes the effective\npermittivity of the metamaterial more than 400 %. This significant modulation\nis more pronounced in ENZ region and we confirm this by the 2TM. The realized\nultrafast modulation in effective permittivity, along with the ultrashort\nrelaxation time of 3.3 ps, opens a new avenue towards ultrafast photonic\napplications.\n