Novel nanowire lasers for light-speed data transfer

Scientists have developed simple new way to produce nanoscale wires that can serve as tiny, tunable lasers, an advance that may lead to light-speed data transmission in computing devices.
The nanowires, with diameters as small as 200 nanometres and a blend of materials that has also proven effective in next-generation solar cell designs, were shown to produce very bright, stable laser light.
Light can carry far more data, far more rapidly than standard electronics - a single fibre in a fibre-optic cable, measuring less than a hair's width in diameter, can carry tens of thousands of telephone conversations at once, for example.

Standard techniques that produce nanowires can require expensive equipment and exotic conditions, such as high temperatures, and can suffer from other shortcomings.
Researchers at the Lawrence Berkeley National Laboratory in US developed a simple chemical-dipping solution process to produce a self-assembled blend of nanoscale crystals, plates and wires composed of cesium, lead and bromine.
The same chemical blend, with a molecular architecture composed of cube-like crystal structures, has also proven effective in an emerging wave of new designs for high-efficiency solar cells.

"The whole purpose of developing nano-sized lasers is to interface photonic (light-based) devices with electronic devices seamlessly. Today, these photonic devices can be bulky," said Peidong Yang, from Berkeley Lab's who led the research.

Conventional combinations of materials used to make nanolasers have shortcomings that can include limited tunability, low brightness or costly manufacturing processes.
In the latest research, the team discovered how to produce nanowires by dipping a thin lead-containing film into a methanol solution containing cesium, bromine and chlorine heated to about 50 degrees Celsius.
A mix of cesium lead bromide crystalline structures formed, including nanowires with a diameter from 200 to 2,300 nanometres (0.2 to 2.3 microns) and a length ranging from 2 to 40 microns.
Select nanowires used in the experiment were placed on a quartz base and excited by another laser source that caused them to emit light.

Researchers found that the nanowire lasers emitted light for over 1 billion cycles after being hit by an ultrafast pulse of visible, violet light that lasted just hundredths of quadrillionths of seconds, which demonstrated remarkable stability, Yang said.
Yang said to his knowledge these nanowires may be the first to emit laser light using a totally inorganic (not containing carbon) blend of materials.
Researchers demonstrated that the nanowire lasers could be tuned to a range of light including visible green and blue wavelengths.
The study was published in the journal PNAS.