Subwavelength 3D terahertz imaging with a single-pixel laser transceiver

Area of Science:

• Optics and Photonics
• Materials Science
• Imaging Technology

Background:

• Terahertz (THz) imaging offers non-destructive material inspection capabilities.
• Practical THz imaging is hindered by resolution limitations, particularly in lateral and axial dimensions.

Purpose of the Study:

• To develop a single-pixel THz imaging system with enhanced resolution beyond conventional limits.
• To demonstrate the potential of laser feedback interferometry for high-fidelity THz imaging.

Main Methods:

• A single-pixel THz imaging system was designed using a confocal microscope architecture.
• A quantum cascade laser served as both transmitter and phase-sensitive receiver.
• Laser feedback interferometry was employed for phase-sensitive detection and imaging.

Main Results:

• Achieved a twofold improvement in lateral resolution (to λ/2) and a two-order-of-magnitude enhancement in axial resolution (to beyond λ/5).
• Generated a 0.5 megapixel image in under three minutes, outperforming existing THz imagers.
• Enabled simultaneous amplitude and phase image acquisition with a custom visualization method for enhanced material characterization.
• 3D tomographic analysis revealed subwavelength features in a silicon chip.

Conclusions:

• The developed system overcomes diffraction limits for THz imaging.
• Demonstrated rapid, high-fidelity imaging of subwavelength features, advancing non-destructive material analysis.
• Laser feedback interferometry is a promising technique for next-generation THz imaging systems.