doi:10.1038/nindia.2016.49 Published online 19 April 2016
Scientists at the Indian Institute of Science (IISc), Bangalore, have designed a new material that can convert very low intensities of light, such as sunlight, into strong laser beams1. These nano-sized semiconductor material or quantum dots have the potential to transform the development of powerful lasers.
Conventionally, very intense light is used to drive most laser devices. The researchers report that this new material can convert very low intensities of light into strong laser beams.
“The material is a nano-sized semiconductor particle that can strongly absorb light," says lead scientist Anshu Pandey from the Solid State and Structural Chemistry Unit of IISc. When a few of these quantum dots are put together, they re-emit light in a single direction, thereby acting as a laser, he says.
Under conditions of extremely low levels of continuous wave illumination, this new class of quantum dots exhibited 'gain'. The researchers report thresholds as low as 74 mW/cm2 in lasers made from the material. "Due to their strong optical absorption as well as low lasing threshold, these materials could possibly convert light from diffuse, polychromatic sources into a laser beam." the report says.
The researchers devised a theoretical model that predicted excellent laser performance in a semiconductor nanoparticle with particular physical attributes. They then designed and synthesized the material and built laser devices out of it. This will open up the possibility of designing efficient laser sources that can emit small amounts of light, they say.
1. Iyer, V. H. et al. Low threshold quantum dot lasers. J. Phys. Chem. Lett. 7, 1244–1248 (2016)