Terahertz Modulators Based on Silicon Nanotip Array

As an attractive applications of terahertz (THz) radiation, imaging with THz technique stands at the focus of current interest. THz spatial modulators are key issue for fast imaging with a single detector. Here, for the first time, the silicon nanotip (SiNT) arrays are reported that can be utilized as antireflection layers for the THz wave to achieve a low-loss and spectrally broadband optical-driven THz modulator. Compared with the modulator fabricated with bare silicon, a 2-3-time larger modulation depth is achieved in SiNT modulator. Moreover, it is found that the intrinsic THz transmission of SiNT is as high as 90%, which is much higher than that of bare silicon. The theoretical simulation results reveal that a strong antireflection effect induced from SiNT layer plays a crucial role in enhancing the properties of modulator. The SiNT-based optical-driven THz modulator with low loss and high modulation depth is promising for potential application to THz imaging.