Ultrafast terahertz modulator based on metamaterial-integrated WSe2 thin-films

Semiconducting TMDs are promising candidates for THz optoelectronic devices with their ultrafast carrier dynamics and large modulation depths stemming from high photo-induced carrier concentration. In this work, we exploit the ultrafast carrier recombination in photoexcited WSe
₂
thin films for active THz modulation. The THz absorption was modelled as a sum of a free carrier Drude term and a Lorentzian oscillator for excitonic bound carriers. Based on this, we explore a THz modulator based on a metamaterial structure capacitively coupled to a CVD grown WSe
₂
film. While the THz absorption upon photoexcitation is strong close to the exciton resonance, the modulation response is limited by free carriers.