Electrically Reconfigurable Micromirror Array for Direct Spatial Light Modulation of Terahertz Waves over a Bandwidth...

Area of Science:

• Optics and Photonics
• Terahertz Technology
• Microelectromechanical Systems (MEMS)

Background:

• Terahertz (THz) waves offer unique properties for imaging and sensing.
• Developing efficient spatial light modulators (SLMs) is crucial for controlling THz beams.
• Existing THz-SLMs face challenges in bandwidth, contrast, and reconfigurability.

Purpose of the Study:

• To design, fabricate, and experimentally investigate a novel spectrally wide-band THz-SLM.
• To achieve high modulation contrast and arbitrary spatial pixelization for THz waves.
• To demonstrate the capability of reconfigurable grating for THz spatial modulation.

Main Methods:

• Fabrication of a 768-actuatable mirror array (220 μm x 100 μm each).
• Utilizing residual stress in multi-layers for mirror actuation (35° inclination).
• Applying bias voltage (37 V) for mirror switching and hysteretic control.

Main Results:

• Demonstrated spectrally wide-band operation from 0.97 THz to 2.28 THz.
• Achieved >50% modulation contrast across the band, peaking at 87% (1.38 THz).
• Enabled arbitrary spatial pixel sizes through mirror grouping and demonstrated reconfigurable grating.

Conclusions:

• The developed THz-SLM provides effective spatial modulation of terahertz radiation.
• The design offers high contrast and flexibility in spatial pixel configuration.
• This technology advances capabilities for THz imaging, sensing, and communications.