Semiconductor nanolaser

2020: Creation of the semiconductor nanolaser working in the visible range at the room temperature

The international group of scientists which researchers from the ITMO University entered, announced creation of the compact semiconductor nanolaser working in the visible range at the room temperature. As authors of a research note, the laser is a nanoparticle of a perovskite of 310 nanometers in size (it by more than 3000 times less than one millimeter), capable to radiate coherent green light at the room temperature. The green part of a visible range which was considered as earlier problem for nanolasers obeyed scientists. On June 5, 2020 reported about it in ITMO.

"In modern area of light-emitting semiconductors there is such concept as "Green gap" ("a green failure"). When in green area of a range there is a falling of quantum efficiency at standard semi-conductor materials for LEDs, and it is extremely difficult to make the full-fledged nanolaser working at the room temperature on their basis", 'Sergey Makarov, the coauthor of work, the chief researcher of physics and technology faculty of the ITMO University noted'

The team of the St. Petersburg researchers selected from quality of material for the nanolaser a perovskite. The traditional laser consists of two basic elements – the active environment which allows to generate laser radiation and the optical resonator allowing to hold electromagnetic energy inside long time. The perovskite can integrate in itself these properties – the nanoparticle of a cubic form is capable to execute both a role of the active environment, and a resonator role.

As a result scientists managed to receive a nanoparticle of 310 nanometers in size which at excitation by its femtosekundny laser is capable to support laser generation at the room temperature.

"For pumping of the nanolaser we used femtosekundny laser impulses and we irradiate with them in a microscope a single nanoparticle while at a certain intensity we do not overcome lasing threshold. Then the nanoparticle also begins to work as the full-fledged laser. We showed that such laser works at least at an extent of millions of acts of pumping as external impulses", 'Ekaterina Tiguntseva, the coauthor of work junior researcher of the ITMO University noted'

The feature of the received nanolaser consists not only in its sizes. Matter also in as far as it well holds in itself(himself) energy of forced radiation to provide sufficient gain of electromagnetic fields for emergence of laser generation.

"All idea is that laser generation is a threshold process, i.e. you shine with the external laser on a particle, and at some certain, "threshold", intensity of an external source the particle begins to generate laser radiation. If light very badly keeps inside, then you however many shone, never receive laser generation. In the previous works with other materials and systems, but the similar ideas, showed that it is possible to use Mi's resonances of the fourth and fifth orders - it means that wavelength in material kept within in resonator four or five of times, at a frequency of laser generation. We showed that our particle radiates on Mi's resonance of the third order. In other words, we can achieve coherent forced radiation if wavelength in a perovskite keeps within in a particle only three times", 'Kirill Koshelev, the coauthor of work junior researcher of the ITMO University noted'

The nanoparticle works as the laser not with some special pressure or extremely low temperature. All described effects managed to be observed with a standard atmospheric pressure and room temperature. It can involve specialists who are engaged in creation of the optical chips, sensors and other devices using light for transfer and information processing. Including it can be used for creation of chips for the optical computer.

Feature of the lasers working in the visible range is that they, other things being equal, less, than red and infrared radiators of similar characteristics. The size of the radiator is cubic dependent on the radiation wavelength and as the wavelength of green light is three times less, than infrared, and the limit of miniaturization also stretches for green nanolasers further. It is important for creation compact a component for future optical computing systems.

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