Terahertz hyperspectral imaging with dual chip-scale combs

TL;DR

This paper demonstrates a compact, chip-scale terahertz hyperspectral imaging system using dual quantum cascade laser combs, enabling fast, coherent, and scalable imaging suitable for biomedical and pharmaceutical applications.

Contribution

It introduces a novel dual-chip terahertz quantum cascade laser comb system for hyperspectral imaging, reducing system complexity and size.

Findings

Achieved 220 GHz bandwidth at 3.4 THz with ~10 μW per line.

Demonstrated free-running, coherent dual comb operation.

Enabled fast, scalable hyperspectral imaging.

Abstract

Hyperspectral imaging is a technique that allows for the creation of multi-color images. At terahertz wavelengths, it has emerged as a prominent tool for a number of applications, ranging from non-ionizing cancer diagnosis and pharmaceutical characterization to non-destructive artifact testing. Contemporary terahertz imaging systems typically rely on non-linear optical down-conversion of a fiber-based near-infrared femtosecond laser, requiring complex optical systems. Here, we demonstrate hyperspectral imaging with chip-scale frequency combs based on terahertz quantum cascade lasers. The dual combs are free-running and emit coherent terahertz radiation that covers a bandwidth of 220 GHz at 3.4 THz with ~10 {\mu}W per line. The combination of the fast acquisition rate of dual-comb spectroscopy with the monolithic design, scalability, and chip-scale size of the combs is highly appealing for future imaging applications in biomedicine and in the pharmaceutical industry.