Researchers from ITMO University, the Far Eastern Federal University (FEFU), the Image Processing Systems Institute of RAS, and Tokai University (Japan) have discovered a way to fashion microcrystals into desired shapes for further use in the production of lenses and other optoelectronic elements without loss of quality.
This research opens up new opportunities for the creation of microoptical elements that could be used in microchips and other optoelectronic devices. A paper on the research was published in Laser & Photonics Reviews.
Perovskites are materials that are actively used in optical systems, such as lasers of solar power systems. Today, it’s not considered viable for commercial use because all existing perovskite processing methods have a significant deteriorating effect on the material’s optical qualities.
“You could liken it to jewelry: it’s not just about the quality of a diamond, but the way it’s cut, too,” explains Sergey Makarov, dean of the Faculty of Photonics at ITMO University. “You need to treat the stone, giving it a new shape while preserving its qualities. It’s the same with perovskites – they need to be processed before being turned into, say, a microlens or any other optical element. But we also have to make sure not to diminish its functional qualities, most of all its optical transparency and luminescence.”
The scientists have suggested using ultra-short (femtosecond) laser pulses. Since perovskites have relatively poor heat conductivity properties, the scientists were able to laser-etch the necessary parts of the crystal without damaging nearby fragments of its structure. Thus, they were able to cut the monocrystals into lenses – and other elements used in optical systems – without harming their optical and light-emitting qualities.
“By using the method we developed, we were able to form various optical microstructures – different microlenses, subwave diffraction gratings with a period significantly smaller than the wavelength of optical radiation, etc. But perovskite optical elements can be used not just as passive devices: when there’s a need to deflect a beam or focus it into a diffraction limit, they can also be used as functional elements of more complex active optical devices: microlasers, ultrafast modulators, and other parts of cutting-edge optical chips,” says Alexey Zhizhchenko, a senior researcher at FEFU and the Image Processing Systems Institute.