A method for producing high-power laser radiation necessary for the development of transport drones has been invented by Russian scientists at the Ioffe Physical-Technical Institute of the Russian Academy of Sciences in St Petersburg.
Transport drones that have been created recently can only work when using laser LiDARS (Light Detection And Ranging). In effect, these lasers collect data about a surface by measuring the “bounce back” time of reflected laser beams to the receiver.
The main difficulty in the use of LiDARS is that to "view" an object hundreds of meters away in whatever weather and conditions, a great deal of power is needed for the laser to be sufficiently bright while operating at nanosecond speeds. At present, fiber and solid-state lasers are used in LiDARS but because they need an additional "pumping" stage (to transfer energy from an external source to the laser), they are inefficient.
The institute's scientists managed to get rid of "an extra stage in the chain of converting energy for the power source into energy for laser radiation," said Sergei Slipchenko, senior researcher at the Ioffe Institute's Laboratory of Semiconductor Laser Diodes.
According to him, they have "proposed an alternative".
"We carried out calculations into the interaction processes between current power and light sources in heterostructures (such as those grown on a substrate, consisting of layers of various materials) and high-power semiconductor laser crystals. Based on this, new designs of semiconductor heterostructures and laser crystal designs were generated for subsequent experimental implementation," Slipchenko added.
New, optimized layers of heterostructures, consisting of different compositions, resulted in minimal energy loss. Furthermore, the scientists have managed to create a technology for so-called selective epitaxy (a type of crystal growth) for high-power lasers, when heterostructures can be grown on a specially prepared substrate.
As a result of the breakthrough research, the efficiency of high-power semiconductor lasers exceeded 70 percent, which is twice the efficiency of solid-state and fiber lasers. The team of researchers also managed to obtain laser pulses with a duration of 100 nanoseconds and with a peak power of more than 1 kilowatt from a surface measuring fractions of square centimeters.
Nikita Pikhtin, associate professor at the Department of Photonics at LETI and head of the Ioffe Institute's Center for Nanostructure Physics, explained that in high-power lasers, the size of the element and the emitting region must be larger, so that it can convert a greater amount of energy into light.
The next stage of the research, which was carried out with the financial support of the Russian Science Foundation, will be to increase the spectral brightness of the lasers.