Researchers have taken a major step toward bringing terahertz frequencies out of their hard-to-reach region of the electromagnetic spectrum and into everyday applications. In a new paper, the researchers demonstrate a first-of-its-kind terahertz laser that is compact, operates at room temperature, and can produce 120 individual frequencies spanning the 0.25 - 1.3 THz, far more range than previous terahertz sources.

The laser could be used in a range of applications, such as skin and breast cancer imaging, drug detection, airport security, and ultrahigh-capacity optical wireless links.

The research was conducted by a team at the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS) in collaboration with the DEVCOM Army Research Lab and DRS Daylight Solutions.

“This is a leap-ahead technology for generating terahertz radiation,” said Federico Capasso, the Robert L. Wallace Professor of Applied Physics and Vinton Hayes Senior Research Fellow in Electrical Engineering at SEAS and senior author of the paper. “Thanks to its compactness, efficiency, wide tuning range, and room temperature operation, this laser has the potential to become a key technology to bridge the terahertz gap for applications in imaging, security, or communications.”

The terahertz frequency range – which sits in the middle of the electromagnetic spectrum between microwaves and infrared light — has remained difficult to reach for applications because most terahertz sources are either very bulky, inefficient, or rely on low-temperature devices to produce these elusive frequencies with limited tuning.