Open AccessAll-optical spatial terahertz modulator with surface-textured and passivated silicon
Author(s) -
Yulian He,
Yuansheng Wang,
Mo Li,
Qinghui Yang,
Zhi Chen,
Jian Zhang,
Qiye Wen
Publication year - 2021
Publication title -
optics express
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.394
H-Index - 271
ISSN - 1094-4087
DOI - 10.1364/oe.419299
Subject(s) - materials science , terahertz radiation , optoelectronics , modulation (music) , optics , silicon , passivation , carrier lifetime , image resolution , nanotechnology , layer (electronics) , physics , acoustics
For a Si-based all-optical spatial terahertz modulator (STM), an enhanced modulation efficiency under low illumination density would be of great significance to exploit the competence of THz technology in real-world applications. We presented here an implementation of such a device by microtexturing and passivating the Si surface, forming a truncated pyramidal array (TPA). This TPA structure with SiO 2 passivating coatings not only decreases light reflectance and expands the active area for THz modulation but also remarkably increases the photogenerated carrier lifetime. These 3-fold benefits render Si-TPA superior to bare-Si with respect to the achievable modulation efficiency, especially at low irradiation power. Furthermore such a Si-TPA device is also more applicable than its counterpart that is only passivated by SiO 2 nanocoatings, even though the Si-SiO 2 has a slightly increased modulation efficiency. These periodically aligned pyramids resembled as a mesa array significantly suppress the lateral diffusion induced by longer diffusion, resulting in an equivalent resolution of bare-Si. This novel Si-TPA based STM is highly desired for realizing a high-performance THz imager and provides a feasible approach to breaking the trade-off between resolution and modulation efficiency.