Dynamic dual-mode terahertz device with nonvolatile switching for integrated on-chip and free-space applications

Area of Science:

• Photonics and Metamaterials
• Terahertz Technology
• Plasmonics

Background:

• Terahertz (THz) communication systems require devices for simultaneous control of surface plasmon polaritons (SPPs) in the near-field (NF) and propagating waves in the far-field (FF).
• Existing THz devices suffer from volatile operation, limited functionality, and inability to integrate NF and FF control.

Purpose of the Study:

• To develop a nonvolatile, reconfigurable THz metasurface platform for on-demand dual-channel modulation.
• To overcome the limitations of single-function devices and integrate NF and FF functionalities.

Main Methods:

• Utilized the phase-change material Ge2Sb2Te5 (GST) and its distinct conductivity states (amorphous and crystalline) for switching functionalities.
• Designed and experimentally validated two devices demonstrating dynamic transitions between NF SPP manipulation and FF wavefront engineering.

Main Results:

• Achieved energy-efficient, nonvolatile switching between NF SPP focusing/anomalous focusing and FF vortex beam generation/holographic imaging.
• Demonstrated simultaneous amplitude and phase control for both SPPs and free-space waves.
• Validated nonvolatile state retention exceeding 10 years.

Conclusions:

• The developed GST-based metasurface platform enables unprecedented dual-channel modulation in the THz regime.
• This technology bridges on-chip plasmonics and free-space THz systems.
• Offers transformative potential for 6G communication, secure data storage, and multifunctional metasensors.