Google Play icon

Tesearchers develop ‘metasurface’ laser for terahertz range

Share
Posted December 20, 2015

Researchers at the UCLA Henry Samueli School of Engineering and Applied Science have identified a new way to make a semiconductor laser that operates at terahertz frequencies. The breakthrough could lead to development of a new class of high-quality, powerful lasers for use in space exploration, military and law enforcement efforts and other applications.

The terahertz range of frequencies occupies the space on the electromagnetic spectrum between microwave and infrared. Terahertz waves can be used to analyze plastics, clothing, semiconductors and works of art without damaging the materials being examined; for chemical sensing and identification; and to investigate the formation of stars and composition of planetary atmospheres.

Unlike a simple mirror, the metasurface developed in Benjamin Williams’ lab amplifies terahertz waves as well as reflecting them. Image credit: UCLA Engineering

Unlike a simple mirror, the metasurface developed in Benjamin Williams’ lab amplifies terahertz waves as well as reflecting them. Image credit: UCLA Engineering

Researchers led by Benjamin Williams, a UCLA associate professor of electrical engineering, have created the first vertical-external-cavity surface-emitting laser, or VECSEL, that operates in the terahertz range. VECSELs that use visible light have been used extensively to generate high-powered beams, but the technique has not previously been adapted for terahertz frequencies.

To make it possible to build an external cavity laser with a high-quality beam, the UCLA researchers created a VECSEL with a “reflectarray metasurface mirror.” The device is so named because it is made up of an array of many small antenna-coupled laser cavities such that when a terahertz wave hits the array, it doesn’t “see” the cavities, but rather is reflected as if it were being reflected from a simple, flat mirror. Unlike a simple mirror however, the mirror amplifies terahertz waves as well as reflecting them.

“This is the first time a metasurface and a laser have been combined,” Williams said. “The VECSEL approach provides a route to have higher output powers simultaneously with excellent beam quality in the terahertz range. The metasurface approach further allows one to engineer the beam to have the desired polarization, shape and spectral properties.”

The research was published in Applied Physics Letters.

Creating a beam that is symmetrical and straight over large distances and changing thermal conditions is a challenge for many semiconductor lasers, but particularly for terahertz quantum cascade lasers, which usually use metal laser cavities with dimensions much smaller than the wavelength.

Luyao Xu, a graduate researcher in Williams’ lab and lead author of the study, said, “By using this amplifying metasurface as part of the external cavity, not only can we improve the beam pattern, but we can also introduce new functionality to this laser with different cavity designs. For example, by using a freestanding wire-grid polarizer, or filter, as a second mirror, we could optimize the lasers’ output power and efficiency simply by rotating the polarizer.”

Xu said the researchers already are working on several new designs to further advance the technology.

Source: UCLA

Featured news from related categories:

Technology Org App
Google Play icon
86,173 science & technology articles

Most Popular Articles

  1. Scientists Reverse Dementia in Mice with Anti Inflammatory Drugs (December 5, 2019)
  2. NASA Scientists Confirm Water Vapor on Europa (November 19, 2019)
  3. How Do We Colonize Ceres? (November 21, 2019)
  4. Universe is a Sphere and Not Flat After All According to a New Research (November 7, 2019)
  5. Scientists created a wireless battery free computer input device (December 1, 2019)

Follow us

Facebook   Twitter   Pinterest   Tumblr   RSS   Newsletter via Email