Temporally-multiplexed dual-frequency terahertz imaging at kilohertz frame rates

TL;DR

This paper introduces a high-speed dual-frequency terahertz imaging method using atomic vapour, achieving 1000 fps and enabling potential hyperspectral imaging for diverse applications.

Contribution

A novel temporally-multiplexed THz imaging technique using laser frequency switching for rapid, multi-frequency imaging at kilohertz frame rates.

Findings

Achieved video rates of 1,000 frames per second for dual THz frequencies.

Demonstrated sequential imaging of two distinct THz frequencies using atomic vapour.

System scalability to more frequencies for hyperspectral imaging.

Abstract

We present a temporally-multiplexed dual-colour terahertz (THz) imaging technique using THz-to-optical conversion in atomic vapour. By rapidly alternating the pump laser frequency, we sequentially excite two atomic states, each absorbing a different THz frequency: 0.5 THz and 1.1 THz. Each THz field induces optical fluorescence at a distinct wavelength, enabling the creation of a sequence of alternating, interleaved images for each frequency. Synchronizing the laser switching with camera acquisition allows video capture at 1,000 frames per second for both frequencies. The system's speed is limited only by laser power and fibre switching hardware. The presented method can be scaled to image more THz frequencies through the addition of further laser frequencies, paving the way for THz hyperspectral imaging in many real-world settings.