Probing beam coherence via terahertz metasurface

Area of Science:

• Optics and Photonics
• Metamaterials
• Terahertz Technology

Background:

• Terahertz (THz) metaoptics is rapidly advancing.
• Simulating metasurface responses under incoherent illumination is complex.
• Probing spatial coherence of THz beams is crucial for various applications.

Purpose of the Study:

• To investigate a metasurface for probing the spatial coherence of incident THz beams.
• To address challenges in simulating and experimenting with incoherent THz illumination.
• To explore potential applications of the designed metasurface.

Main Methods:

• Utilized an angular spectrum averaging technique based on the Van Cittert-Zernike theorem.
• Related the wavevector distribution of the incident beam to spatial coherence width.
• Experimental measurements were conducted and compared with simulation results.

Main Results:

• Experimental measurements showed good agreement with simulation results.
• Demonstrated that the metasurface transmission dip depth increases as spatial coherence width decreases.
• A metasurface-based spatial low-pass filter was discussed.

Conclusions:

• The designed THz metasurface can effectively probe spatial coherence.
• The metasurface exhibits potential for THz imaging and spatial filtering.
• Applications include improving signal-to-noise ratio in optical communication.