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An Optically Tunable THz Modulator Based on Nanostructures of Silicon Substrates
Chen Mo1,2, Jingbo Liu1, Dongshan Wei1
1School of Electrical Engineering and Intelligentization, Dongguan University of Technology, Dongguan 523808, China.
Sensors (Basel, Switzerland)
|April 17, 2020
Summary
Silicon nanostructures like nanotips and nanoholes show promise as all-optical broadband terahertz (THz) modulators. Nanotip structures achieved a high modulation depth, offering a guide for future THz device design.
Area of Science:
- Optoelectronics
- Nanotechnology
- Terahertz (THz) technology
Background:
- Nanostructures enhance light absorption and photocarrier generation through multireflection.
- All-optical broadband THz modulators are crucial for advanced THz applications.
Purpose of the Study:
- To propose and simulate silicon nanostructures (nanocylinders, nanotips, nanoholes) as all-optical broadband THz modulators.
- To compare the modulation properties of different nanostructures under varying illumination wavelengths.
Main Methods:
- Finite element method (FEM) calculations were used to simulate modulation properties.
- A graded index layer model was established to explain simulation results.
Main Results:
- All nanostructures exhibited suppressed light reflectance, with nanotip showing the lowest (0.63%) at 2 THz.
- The nanotip modulator achieved 91.63% modulation depth at 2 THz under 808 nm illumination.
- Modulation performance decreased at shorter wavelengths (532 nm), with nanohole structures outperforming nanotips.
Conclusions:
- Silicon nanostructures are effective for all-optical broadband THz modulation.
- Nanotip structures show superior performance under specific illumination conditions (808 nm).
- The study provides theoretical guidance for designing optically tunable broadband THz modulators.
