Terahertz spectroscopy has surmounted many of the technological challenges that have prevented its wider acceptance, and while most of the interest in terahertz is research oriented, industrial applications are also developing in niche areas. Complete commercial systems came onto the market about 15 years ago, and the vendor base is also expanding, helping to evolve the technology into a more functional form.

Terahertz spectroscopy utilizes a previously little used segment of the electromagnetic spectrum with frequencies around 1 THz (tera = 10^12). Although there is no rigid definition, the band covers frequencies from about 0.3 THz to 20 THz. This corresponds to wavelengths of 1 mm down to about 0.01 mm. Roughly speaking, this band sits between the far infrared and microwave radiation. Like the infrared, the terahertz band is useful for probing vibrational and rotational modes of molecules, making spectroscopy possible. One advantage of terahertz is that these waves can penetrate numerous materials, so materials can be identified even if they are enclosed in packaging or hidden from view. The main disadvantage of the technique is that it has been difficult to produce sources and detectors of the radiation. While manufacturing techniques and products are improving, the costs are still quite considerable.

The capability to see through outer layers enables many of the niche applications that exist for terahertz spectroscopy. In semiconductors and electronics, the systems can be used to investigate electronics and chipsets that are inside devices. This process is used for QC checks with consumer electronics. The terahertz waves can stimulate an electrical signal in semiconductor devices, and the re-radiated pulse can be analyzed to determine whether the electrical contacts are intact in the device. Pharmaceutical products can be analyzed inside packaging in a nondestructive way. Other applications involve the analysis of thin films and coatings in samples ranging from plastics to pharmaceuticals. Terahertz can be particularly useful for opaque materials that do not lend themselves well to other techniques. This capability to see through outer layers also enables security applications in detecting explosives.

But terahertz spectroscopy is still very much an academic research tool and is used in a variety of materials research in photonics, electronics, magnetic materials, plastics and other sample types. In the life sciences, medical imaging is an exciting area of research, as studies have shown that cancer cells can be discriminated from healthy cells using terahertz.

TeraView is the leading vendor in this area and has the broadest application base. The company also benefits from a distribution arrangement with Bruker. Advantest is more focused on semiconductor and electronics inspection applications. Other significant vendors include Hamamatsu, Menlo Systems, Toptica and Zomega. Total 2015 market demand for lab terahertz spectroscopy was about $30 million.

Terahertz Spectroscopy at a Glance:

Leading Suppliers

• TeraView

• Advantest

• Luna Innovations

Largest Markets

• Academia

• Semiconductor & Electronics

• Pharmaceuticals

Instrument Cost

• $80,000-$450,000