Researchers from Agency for Science, Technology and Research (A*STAR), Singapore have realized lasing in nanoscale semiconductor structures by using an array of nanoantennas.
A promising method to develop nanoscale lasers is to use arrays of tiny structures made from semiconductors with a high refractive index. Such structures act as tiny antennas that resonate at specific wavelengths. However, it is challenging to use these semiconductor to construct a cavity, where light bounces around while being amplified. Now, the A*STAR team developed a tiny laser comprising an array of nanoscale semiconductor cylinders. The research published in the journal Nature Nanotechnology on September 13, 2018, is a pioneering experiment of lasing achieved in non-metallic nanostructures. The findings could lead to development of miniature lasers usable in a wide range of optoelectronic devices.
The team used a highly unusual type of standing wave that remains in one spot despite coexisting with a continuous spectrum of radiating waves that can transport energy away. The researchers initially planned to create a laser that was based on the diffractive resonances in the array. However, fabrication and sample tests revealed strong enhancement at a different wavelength from expected. Moreover, several simulations and analysis revealed that the team had created the novel waves. The A*STAR research spanned for five years. According to Arseniy Kuznetsov, researcher at the A*STAR Institute of Materials Research and Engineering, “It was a race against time, since other groups were also working on developing active nanoantennas. Until now, lasing hasn’t been realized in nanoantenna structures. So it’s a big step for the dielectric nanoantenna community.”
The novel laser has several advantages over other kinds of lasers. The beam of the A*STAR laser is narrow and well-defined and its direction can be easily controlled. Such maneuverability is required in device applications. Moreover, the laser is highly transparent as the nanocylinders are quite sparsely distributed. The transparency of the laser is beneficial for multilayer devices that contain other optical components. The team is focused on further research to develop electrically-excited lasers that would be a major advancement towards development of commercial nanolasers.