Abstract
We propose an efficient optically actuated THz modulator based on an ultrathin epsilon-near-zero (ENZ) slab photogenerated in an InAs semiconductor. We experimentally demonstrate a modulation depth of 90% at 1 THz obtained with a continuous laser at irradiation lower than 10 W cm À2. Beyond the strong attenuation of the THz transmission provided by the ENZ absorption effect, we also report a broadband modulation of the THz waves from 1 to 10 THz. In addition, our experimental results show that the cutoff frequency of 3 dB attains 2 MHz in the dynamic modulation regime.