With the importance of short distance optical interconnects for improving data centres’ performance, a team of researchers have discovered the first step towards building electrically pumped nanolasers (or light-based sources). These lasers are critical in the development of integrated photonic based short-distance optical interconnects and sensors.

The team including Arka Majumdar, University of Washington assistant professor of Electrical Engineering and Physics and Xiaodong Xu, assistant professor of Materials Science and Engineering and Physics, demonstrated this first step through cavity-enhanced electroluminescence from atomically thin monolayer materials. The thinness of this material yields efficient coordination between the two key components of the laser. Both the cavity-enhanced electroluminescence and material will allow energy-efficient data centres and support high performance parallel computing.

 
Research team (cr) Figure 1: Assistant professors Arka Majumdar (left) and Xiaodong Xu (right) have discovered how to improve data centre’s performance through light-based sources.  

The recently discovered atomically thin semiconductors have generated significant interest due to showing light emission in the 2D limit. However, due to the extreme thinness of this material, its emission intensity is usually not strong enough, and it is important to integrate them with photonic devices (nanolasers, in this case) to get more light out.

“Researchers have demonstrated electroluminescence in this material [atomically thin monolayer],” Majumdar said. “Last year, we also reported the operation of an ultra-low threshold optically pumped laser, using this material integrated with nano-cavity. But for practical applications, electrically driven devices are required. Using this, one can power the devices using electrical current. For example, you power your laser pointer using an electrical battery.”

 
2D material heterostructure (cr) Figure 2: Heterostructure of 2D material.  

Majumdar and Xu recently reported cavity-enhanced electroluminescence in atomically thin material. A heterostructure of different monolayer materials are used to enhance the emission. Without the cavity, the emission is broadband (unidirectional) and weak. A nano-cavity enhances the emission and also enables single-mode (directed) operation. This allows direct modulation of the emission, a crucial requirement for the data communication.

These structures are of current scientific interest and are considered the new “gold rush” of condensed matter physics and materials science. Their current result and the previous demonstration of optically pumped lasers show the promise of electrically pumped nanolasers that constitutes the next milestone for this research. This next achievement will improve data centre’s efficiency for optimal performance.

“Our team is currently exploring integration of the monolayer materials with a silicon nitride platform,” Majumdar said. “Through this work, we hope to achieve the coveted CMOS [complementary metal-oxide-semiconductor] compatibility that is the same process by which the computer processors are fabricated today.”