UCLA Researchers Develop Terahertz-Band VCSEL Laser

Researchers at UCLA's Henry Samueli School of Engineering and Applied Science (HSSEAS) have discovered a new way to generate semiconductor lasers that operate at terahertz frequencies (between microwaves and infrared) , Compound Semiconductor reports.

The semiconductor laser, developed by a team led by Benjamin Williams, an associate professor of electrical engineering at UCLA, is the first vertical-external-cavity surface-emitting laser (VECSEL) to operate in the terahertz range. While VECSELs using visible light have been widely used to generate high-power beams, the technique has never been applied to terahertz frequencies.


▲Schematic of a THz metasurface VECSEL

To create an external cavity laser capable of shooting high-quality beams, UCLA researchers developed a VECSEL using a "reflectarray metasurface mirror."

The device is given its name because it consists of a large number of small antenna-coupled laser cavities, so when terahertz waves strike the array, they do not 'recognize' the cavities and behave as if they were striking a simple flat mirror.Because it reflects like a hinge. However, unlike a simple mirror, this mirror not only reflects terahertz waves but also amplifies them.

“This is the first time that a metasurface has been combined with a laser,” said Williams . “The VECSEL approach offers a way to achieve higher power outputs while maintaining excellent beam quality in the terahertz range. The metasurface approach further allows us to control the beam to have the desired polarization, shape, and spectral properties.”

They believe these innovations could lead to the development of a new class of powerful, high-quality lasers for use in space exploration, military and law enforcement efforts, and other applications. For example, they could be used to analyze plastics, clothing, semiconductors, and artwork without damaging the materials being examined; to detect and identify compounds; and to study star formation and planetary atmospheres.

The researchers are already developing several new designs to further advance this technology , Compound Semiconductor added.