Affiliation of Author(s):[1]Dongguan Univ Technol, Sch Elect Engn & Intelligentizat, Dongguan 523808, Peoples R China;[2]Shenzhen Univ, Coll Phys & Optoelect Engn, Shenzhen 518061, Peoples R China;[3]Univ Elect Sci & Technol China, State Key Lab Elect Thin Films & Integrated Devic, Chengdu 610054, Peoples R China
Journal:SENSORS
Key Words:terahertz; modulator; nanostructure; CST simulation
Abstract:Nanostructures can induce light multireflection, enabling strong light absorption and efficient photocarrier generation. In this work, silicon nanostructures, including nanocylinders, nanotips, and nanoholes, were proposed as all-optical broadband THz modulators. The modulation properties of these modulators were simulated and compared with finite element method calculations. It is interesting to note that the light reflectance values from all nanostructure were greatly suppressed, showing values of 26.22%, 21.04%, and 0.63% for nanocylinder, nanohole, and nanotip structures, respectively, at 2 THz. The calculated results show that under 808 nm illumination light, the best modulation performance is achieved in the nanotip modulator, which displays a modulation depth of 91.63% with a pumping power of 60 mW/mm(2) at 2 THz. However, under shorter illumination wavelengths, such as 532 nm, the modulation performance for all modulators deteriorates and the best performance is found with the nanohole-based modulator rather than the nanotip-based one. To further clarify the effects of the nanostructure and wavelength on the THz modulation, a graded index layer model was established and the simulation results were explained. This work may provide a further theoretical guide for the design of optically tunable broadband THz modulators.
Document Type:Article
Volume:20
Issue:8
ISSN No.:14248220
Translation or Not:no