Ultrashort laser pulse technology ushered in a new breakthrough

Lasers are becoming an integral part of countless devices and industries. When a laser beam interacts with the surface of a nanoscale material, it emits a light wave called a plasmon, and the properties of a given plasmon can transmit information. In optical transmission, a laser pumps light into a component called a "saturable absorber" to produce an optical signal.

Yu Yao, an associate professor of electrical engineering at Arizona State University, and her research team at ASU's Photonics Innovation Center have designed a faster and more energy efficient nanoscale laser element called a graphene-plasma hybrid cell Structure Saturated Absorber, or GPSMA.

GPSMA has potential applications in industries such as communications, information processing, spectroscopy and biomedicine. Absorbers can be used to improve 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 saturation absorption, Yu Yao's team incorporated an artificially engineered metal-graphene hybrid material into their development process.

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

They achieved these important results by designing an optical antenna array that focuses light into nanoscale gaps in the material, known as hot spots, to promote absorption. By focusing the laser on these hot spots, they observed improved performance and a reduction in energy consumption.

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

Based on their significantly increased speeds, their new technology will open up new opportunities for infrared laser spectroscopy and high-speed optical signal communications (fiber optic cables and satellite communications).

"Our device can operate at record high speeds," Yu said. "Traditional saturable absorbers can work on nanosecond timescale, but now we can reach about 60 femtoseconds, which is more than 100,000 times faster than before."

GPSMA currently operates at near-infrared wavelengths on the electromagnetic spectrum. Because graphene has a wide optical response, it can extend its spectral coverage to longer wavelengths in the infrared spectral region, which has important implications for molecular spectroscopy and optical communication. However, for longer wavelengths, it has traditionally been more difficult to achieve saturated absorption and generate ultrashort laser pulses. Therefore, the GPSMA design concept can fill such a technical gap.

Yu Yao's team's device has potential applications in the telecommunications, energy and biomedical industries. This absorbent can be used to improve the speed, efficiency and overall performance of fiber optic cables, opening up opportunities to advance data transmission, solar cell performance and disease detection imaging technologies.

Source: OFweek