US scientists build nanolaser from single atomic sheet
University of Washington scientists in collaboration with Stanford University have built a nanometer-sized laser using the tungsten-based semiconductor WSe2 three atoms thick as the gain material that emits light. The technology is described in a paper published in the March 16 online edition of Nature.
Other nanolaser designs use gain materials that are either much thicker or that are embedded in the structure of the cavity that captures light. That makes them difficult to build and to integrate with modern electrical circuits and computing technologies.
The UW version, instead, uses a flat sheet that can be placed directly on top of a commonly used optical cavity. The ultrathin nature of the semiconductor - made from a single layer of a WSe2 - yields efficient coordination between the two key components of the laser.
The UW nanolaser requires 27 nanowatts to kickstart its beam. Other advantages according to the researchers are that it can be easily fabricated, and it can potentially work with silicon components common in modern electronics. Using a separate atomic sheet as the gain material offers versatility and the opportunity to more easily manipulate its properties.
"You can think of it as the difference between a cell phone where the SIM card is embedded into the phone versus one that's removable," said co-author Arka Majumdar, UW assistant professor of electrical engineering and of physics.
"When you're working with other materials, your gain medium is embedded and you can't change it. In our nanolasers, you can take the monolayer out or put it back, and it's much easier to change around," he said.
The researchers hope this and other recent innovations will enable them to produce an electrically-driven nanolaser that could open the door to using light, rather than electrons, to transfer information between computer chips and boards.
Using photons rather than electrons to transfer that information would consume less energy and could enable next-generation computing that breaks current bandwidth and power limitations. The recently proven UW nanolaser technology is one step toward making optical computing and short distance optical communication a reality.
Next steps include investigating photon statistics to establish the coherent properties of the laser's light.
