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.
• Conventional confocal imaging lacks sufficient resolution for subwavelength features.

Purpose of the Study:

• To develop a single-pixel THz imaging system with enhanced resolution.
• To overcome the diffraction limit in THz imaging.
• To enable high-fidelity, rapid material characterization.

Main Methods:

• Utilized a confocal microscope architecture with a quantum cascade laser as transmitter and phase-sensitive receiver.
• Implemented laser feedback interferometry for phase-sensitive detection.
• Developed a custom visualization method linking amplitude and phase to image properties.

Main Results:

• Achieved a twofold improvement in lateral resolution (λ/2) and a two-order-of-magnitude enhancement in axial resolution (beyond λ/5).
• Generated a 0.5 megapixel image in under three minutes, outperforming existing systems.
• Demonstrated subwavelength feature imaging via 3D tomographic analysis of a silicon chip.

Conclusions:

• The developed THz imaging system significantly overcomes resolution limits of conventional lens-based systems.
• Laser feedback interferometry enables rapid, high-fidelity imaging of subwavelength features beyond the diffraction limit.
• The system shows great potential for advanced non-destructive material analysis and inspection.