Arizona State University researchers have made a breakthrough in ultrashort laser pulse technology

From communications and entertainment to manufacturing and healthcare, lasers have revolutionized the way we interact with the world around us. They have become an integral part of our modern lives, pushing the boundaries of innovation as an integral part of countless devices and industries.

The laser produces a narrow beam. When the light from the laser interacts with the surface of the material at the nanoscale, it emits a type of light wave called a plasmon, which, given the properties of the plasmon, can emit an informational signal. In optical transmission, a laser pumps light at a component called a saturable absorber to generate an optical signal.

Yu Yao is an associate professor of electrical engineering in the College of Electrical, Computer and Energy Engineering at Arizona State University's Ira A. Fulton College of Engineering. She and her research team at Arizona State University's Center for Photonics Innovation have designed a faster and more energy efficient nanoscale laser assembly called a graphene-plasma hybrid cell structure-saturable absorber, called GPSMA.

GPSMA has potential applications across the communications, information processing, spectroscopy and biomedical industries. Absorbers can be used to increase speed, efficiency and overall performance to advance data transmission, information processing, biomedical sensing and imaging technologies.

Due to its beneficial properties in optical modulation and saturable absorption, Yao's team has been employing artificially designed metal-graphene hybrid materials in their work.

In a recent article published in the scientific journal ACS Nano, Yao details her lab's integration of a graphene-based saturable absorber and how they have improved the device to reduce power consumption while maintaining ultra-fast response times.

They achieved these remarkable results by designing an optical antenna array that focuses light into nanoscale gaps (called hot spots) in the material to facilitate absorption. By focusing the laser on these hot spots, they observed improved performance and reduced energy consumption.

"Graphene is lightweight and has a fast optical response time, but low single-layer absorption," Yao said. "We designed this device so that the light absorption in the nanoscale hot spot can be increased by more than three orders of magnitude, resulting in not only strong light absorption, but also a saturable absorption effect." With GPSMA, we are making a saturable absorber device that can actually reduce power consumption by nearly two to three orders of magnitude."

Because of its speed, their new technology opens up opportunities for infrared laser spectroscopy and high-speed optical signal communication via fiber-optic cables and satellite communications.

"Our device can operate at record speeds," Yao said. "Traditional saturable absorbers can operate on nanosecond timescales, but now we can get to about 60 femtoseconds, which is more than 100,000 times faster."

GPSMA currently operates at near-infrared wavelengths of the electromagnetic spectrum. Because graphene has a wide optical response, its spectral coverage can be extended to longer wavelengths in the infrared spectral region, which has important implications for molecular spectroscopy and optical communication. However, for longer wavelengths, it is often more difficult to achieve saturable absorbers and produce ultrashort laser pulses. Therefore, the GPSMA design concept can fill this technical gap.

Yao's devices have potential applications in the telecommunications, energy and biomedical industries. Absorbers can be used to improve the speed, efficiency, and overall performance of fiber optic cables, providing opportunities to advance data transmission, solar cell performance, and disease detection imaging technologies.

Source: Laser Network