2D Laser Breakthrough May Open the Door to Next-Generation Photonic Devices

First Posted: Oct 23, 2015 07:29 AM EDT

Scientists have made an exciting breakthrough with 2D lasers. They've created a two-dimensional, excitonic laser that's an important step toward next-generation, ultra-compact photonic and optoelectronic devices.

"Our observation of high-quality excitonic lasing from a single molecular layer of tungsten disulfide marks a major step towards two-dimensional on-chip optoelectronics for high-performance optical communication and computing applications," said Xiang Zhang, one of the researchers, in a news release.

The researchers actually embedded a monolayer of tungsten disulfide into a special microdisk resonator to achieve bright excitonic lasing and visible wavelengths.

So why is this important? Among the most talked about class of materials in the world of nanotechnology today are two-dimensional transition metal dichalcogenides (TMDCs). These 2D semiconductors offer superior energy efficiency and conduct electrons much faster than silicon. In addition, unlike graphene, the other highly touted 2D semiconductor, TMDCs have natural bandgaps that allow their electrical conductance to be switched "on and off," making them more device-ready than graphene. Until now, though, coherent light emission, which is considered essentially for "on-chip" applications, had not been done for this material.

"TMDCs have shown exceptionally strong light-matter interactions that result in extraordinary excitonic properties," said Zhang. "These properties arise from the quantum confinement and crystal symmetry effect on the electronic band structure as the material is thinned down to a monolayer. However, for 2D lasing, the design and fabrication of microcavities that provide a high optical mode confinement factor and high quality, or Q, factor is required."

In this case, the researchers designed a microdisk resonator that supports a dielectric whispering gallery mode to give the excitonic laser a high Q factor with low power consumption. Essentially, they created the potential for ultralow-threshold lasing.

The findings could be huge for the future of spintronics or quantum computing. Because they can compete with graphene, TMDCs could be the new material of the future.

The findings are published in the journal Nature Photonics.

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