Scientists first demonstrated the generation of green laser light on the particle of the perovskite material with a size of 310 nanometers. The laser works at room temperature and standard atmospheric pressure — due to this technology may find applications in optical computing systems. Article accepted for publication in ACS Nano, the text placed on the magazine’s website.
Lasers are devices that due to external energy (called energy pumping) generate a narrow directional beam of radiation. The material atoms that are in excited state, is capable under the influence of an external photon with the same energy (equal to the energy of excitation) to emit your photon without absorbing external. Due to this, radiation of a certain energy can be amplified when passing through a material, the atoms are in the excited state, — the active medium of the laser. As the primary radiation in the laser the photons are spontaneously emitted from the same excited atoms is that their energy immediately adopts the desired value. To maintain generation using optical resonator — a device that allows emerging photons immediately leave the active medium, resulting in greatly increases the rate of production and enhances the intensity of the radiation.
To effectively apply lasers in engineering (and especially in optical computing systems), it is necessary to make these devices small and efficient. For these purposes well suited nanoparticles of perovskite materials, which can simultaneously act both as the active medium and an optical resonator. In addition to the fact, nanocrystals of such substances is relatively easy to make — some of them can be synthesized even at room temperature.
The scientific team from Australia, Hong Kong,, USA and Sweden under the leadership of Yuri Civera (Yuri Kivshar) and Sergei Makarov (Sergey Makarov) of the ITMO University for the first time demonstrated laser generation in the visible range for particles CsPbBr3. Nanocrystals of cubic shape with a size from several hundred nanometers (a thousand times smaller than a millimeter) of physics have grown on a sapphire substrate, one at a time using warmed solutions PbBr2 and CsBr. For optical pumping of the crystal, the authors have focused on this ultra-short (duration trillionth of a millisecond) laser pulses with a wavelength of 524 nm, and then collecting the resulting radiation with the aid of special lens and investigated its spectral composition (that is, the measured intensity of radiation at different wavelengths) using a diffraction grating.
It turned out that the crystals from 310 nanometers give a splash of intensity of radiation in the region of green light (wavelength ranges from 520 to 540 nanometers) and the resulting nanolaser work lasts for not less than one million acts of pumping, which indicates the ability of the perovskite particles effectively retain energy — these properties give the material great prospects in the future technical application. The authors note that the first time they were able to achieve resonance, the Mi of the third order — that is put in the cavity of all three wavelengths, whereas in previous studies, there were only the resonances of the fourth and fifth orders. In addition, all of the properties listed nanolaser exhibits at room temperature and normal atmospheric pressure, which also increases the possibility of its use in compact optical devices.
Read more about the use of perovskite materials in nanophotonics can be found in the material “the Majority of discoveries not yet made”, and how they are used in solar cells — in the article “the Horizon of perovskite events”.