Ultrafast All-Optical Switching of Germanium-Based Flexible Metaphotonic Devices

Abstract

Incorporating semiconductors as active media into metamaterials offers opportunities for a wide range of dynamically switchable/tunable, technologically relevant optical functionalities enabled by strong, resonant light–matter interactions within the semiconductor. Here, a germanium-thin-film-based flexible metaphotonic device for ultrafast optical switching of terahertz radiation is experimentally demonstrated. A resonant transmission modulation depth of 90% is achieved, with an ultrafast full recovery time of 17 ps. An observed sub-picosecond decay constant of 670 fs is attributed to the presence of trap-assisted recombination sites in the thermally evaporated germanium film.

Ultrafast all-optical switching of a germanium-based flexible metaphotonic device demonstrates ultrafast modulation of Fano and dipole resonances with a full recovery time of 17 ps. Relaxation of photoexcited carriers occurs with a sub-picosecond time constant of 670 fs, attributed to surface defects in thermally evaporated germanium on the ultrathin flexible metadevice.

http://ift.tt/2D1L6oB