Researchers from Federico Capasso’s lab along with collaborators from MIT and the US Army have developed a compact, tunable laser source for terahertz frequencies, a largely untapped region of the electromagnetic spectrum with exciting applications in imaging and communications. The device combines a quantum cascade laser with a traditional optically pumped far-infrared laser. By tuning the quantum cascade laser emission to the excitation frequencies of the molecular gas used in the device, a near limitless range of terahertz frequencies with powers in the range of 1mW can be accessed. This technology overcomes the shortcomings of traditional terahertz sources in that it is compact (about the size of a shoebox), has an impressive power and frequency range, and can operate at room temperature.

This novel device opens the terahertz range to applications in wireless communications, spectroscopy, and radar. The ability to adjust frequencies to avoid high atmospheric absorption offers promise for telescopes as well as free-space communication networks. In comparison with microwaves, the higher frequency and greater spatial resolution of terahertz radiation can afford future wireless communication systems with greater bandwidth and reduced power requirements. For the analysis and security communities, the size, power and tunability of the technology may be desirable in applications where portability, long-range detection, or higher signal to noise are required.

This work was described in Science and the Harvard Gazette.