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Enhanced terahertz focusing for a graphene-enabled active metalens
Optics Express
|November 13, 2020
Summary
This study introduces a novel hybrid graphene metasurface for terahertz (THz) waves, achieving enhanced focusing efficiency and tunable focal length. The design boosts efficiency by 1.8 times through multi-reflection, paving the way for advanced THz devices.
Area of Science:
- Optics and Photonics
- Materials Science
- Electrical Engineering
Background:
- Graphene-based terahertz (THz) metasurfaces offer advantages like thinness and electrical tunability.
- Existing transmissive THz metasurfaces often exhibit low focusing efficiency.
Purpose of the Study:
- To propose and demonstrate a hybrid metasurface structure for enhanced THz wave focusing.
- To achieve electrical tunability and high efficiency in THz metasurface devices.
Main Methods:
- A hybrid structure combining a graphene-loaded metallic metasurface with orthogonal gratings was designed.
- The multi-reflection effect between the metasurface and grating layers was utilized to enhance focusing.
- Experimental measurements were conducted to evaluate focusing efficiency and focal length tuning.
Main Results:
- The hybrid metasurface demonstrated a 1.8-fold enhancement in focusing efficiency.
- The focal length of the metalens was tunable, increasing by 0.61 mm with applied gate voltage (0 V to 1.4 V).
- The proposed structure effectively addresses the low efficiency issue in transmissive THz metasurfaces.
Conclusions:
- The developed hybrid graphene metasurface offers a promising solution for high-efficiency, reconfigurable THz wave focusing.
- This design opens new possibilities for advanced tunable THz optical components.
- The multi-reflection strategy is effective for improving the performance of THz metasurfaces.
