Scientists create first quantum cascade laser on silicon

WASHINGTON, April 20 (UPI) -- Researchers have managed to install a laser directly on a silicon chip, a breakthrough that could bolster a variety of technologies, including gas sensors and space communication systems.

Scientists have previously integrated diode lasers and silicon chips, but diode lasers aren't able to generate beams at longer wavelengths, diminishing their potential applications.

To improve upon the technology, researchers turned to quantum cascade lasers. The transition brought new problems, however. Previous laser-silicon marriages used silicon dioxide in the integration component known as the waveguide. Silicon Dioxide absorbs longer wavelengths, inhibiting laser beam production.

The research team designed a new waveguide, using a layer of silicon nitride to insulate the new laser from the silicon dioxide.

"Traditionally, silicon photonic devices operate at near-infrared wavelengths, with applications in data transmission and telecommunications," lead researcher Alexander Spott, with the University of California, Santa Barbara, said in a news release.

"However, there is emerging research interest in building these silicon photonic devices for longer mid-infrared wavelengths," Spott continued, "for a range of sensing and detection applications, such as chemical bond spectroscopy, gas sensing, astronomy, oceanographic sensing, thermal imaging, explosive detection, and free-space communications."

As currently configured, the laser uses a lot of energy and wastes a lot of heat all for the production of a relatively weak laser beam. The scientists are now working on improving their prototype.

"We generally hope to improve the design to get higher powers and efficiency," Spott said. "This brings us closer to building fully integrated mid-infrared devices on a silicon chip, such as spectrometers or gas sensors."

Still, if the laser's performance improves, the researchers believe their technology could be quickly scaled for use in the real world.

"Silicon is inexpensive, the fabrication can be scaled up to significantly reduce the cost of individual chips, and many small devices can be built on the same silicon chip -- for example multiple different types of sensors operating at different mid-infrared wavelengths," Spott added.

Spott and his colleagues presented their research this week in Washington, D.C. at the annual Optical Society meeting.