New terahertz source operates at room temperature

Terahertz (THz) radiation has applications in security screening, medical and industrial imaging, agricultural inspection, astronomical research, and other areas.

Traditional methods of generating terahertz radiation, however, usually involve large and expensive instruments, some of which also require cryogenic cooling.

A compact terahertz source - similar to the laser diode found in a DVD player - operating at room temperature with high power has been a goal of the terahertz community for a number of years.

Manijeh Razeghi, Walter P. Murphy Professor of Electrical Engineering and Computer Science at Northwestern University’s McCormick School of Engineering and Applied Science, and her group are said to be close to achieving this goal.

According to the university, terahertz radiation is generated through non-linear mixing of two mid-infrared wavelengths at 9.3 microns and 10.4 microns inside a single quantum cascade laser.

By stacking two different QCL emitters in a single laser, the researchers created a monolithic non-linear mixer to convert the mid-infrared signals into terahertz radiation, using a process called difference frequency generation.