Semiconductor nanolaser

2024: Small nanolaser designed for ultra-compact chips

Scientists from ITMO managed to reduce the size of the nanoparticle from 310 nanometers to 200 (this is 5 thousand times less than a millimeter!). The installation works at room temperature, and you can see the green light emitted by the laser in a standard optical microscope. The development will help in creating the smallest details for digital micro-devices and devices for analyzing health indicators, as well as improve the quality of color reproduction of screens in virtual reality glasses. The university announced this on May 29, 2024.

Nanolasers are lasers that are smaller than the wavelength of light (or photon - particles of light) emitted by them. As a rule, their magnitude in all three spatial dimensions (length, height and width) is calculated in hundreds of nanometers. With the help of such devices, the smallest details for microelectrode devices are created. These include not only, for example, complex computing equipment for laboratories, but also medical devices and even individual components of game consoles. Every year microelectronics becomes more complicated and requires the creation of more and more compact components, but only single installations, due to their size limitations, allow them to be produced.

ITMO scientists have proposed technologies for creating nanolasers that would meet these requirements. The development is a perovskite nanoparticle (a laboratory-created material with a chemical composition of CsPbBr3) in the form of a cuboid. This material has been studied at the university since 2017. During this time, scientists have been able to prove that it is stable, has a high optical gain (allows you to use the energy of light as efficiently as possible), and most importantly, it works best in the green spectrum.

For a long time, this wavelength range has been the most problematic for creating compact lasers, especially on a production scale. This part of the visible spectrum was even given the name green gap ("green pit/space"). However, scientists with the help of perovskite finally managed to resolve this issue. This opened up opportunities for even greater compactization of the nanolaser, as the wavelength of green photons is three times smaller than the infrared ones used in classical microlasers.

Most of the experiments were conducted by ITMO graduate students Mikhail Masharin and Daria Khmelevskaya, led by the project Sergey Makarov, Doctor of Physical and Mathematical Sciences, Head of the Laboratory of Hybrid Nanophotonics and Optoelectronics ITMO.

The key idea of ​ ​ the proposed design of the nanolaser is to use this mechanism of its work by building a strong light-substance connection. This helps to significantly reduce the threshold for its "inclusion." The radiation of the nanolaser is directional in nature, which allows it to be efficiently collected in our optical scheme and recorded on a laboratory spectrometer (a device for fixing, processing and analyzing light waves), said Sergey Makarov, head of the laboratory of hybrid nanophotonics and optoelectronics ITMO.

At this stage of research, scientists have managed to place a perovskite particle on the metal. This opens up the possibilities for creating a nanolaser installation, the operation of which will be activated by electricity, and not by light, as is happening now. Based on such ultra-compact laser diodes with electric "pumping," it will be possible to create micropixels in augmented reality glasses, medical devices for monitoring the state of a person, as well as in multifunctional optical chips.

2020: Building a semiconductor nanolaser operating in the visible range at room temperature

An international team of scientists, which included researchers from ITMO University, announced the creation of a compact semiconductor nanolaser operating in the visible range at room temperature. According to the authors of the study, the laser is a nanoparticle of perovskite measuring 310 nanometers (this is more than 3000 times less than one millimeter), capable of emitting coherent green light at room temperature. Scientists have submitted to the green part of the visible spectrum, which was previously considered problematic for nanolasers. This was reported on June 5, 2020 in ITMO.

"In the modern field of light-emitting semiconductors, there is such a thing as" Green gap. " When in the green region of the spectrum there is a drop in quantum efficiency in standard semiconductor materials for LEDs, and it is extremely difficult to make a full-fledged nanolaser operating at room temperature based on them, " noted Sergey Makarov, co-author of the work, chief researcher at the Faculty of Physics and Technology of ITMO University

A team of St. Petersburg researchers chose perovskite as the material for their nanolaser. A traditional laser consists of two main elements - an active medium that allows you to generate laser radiation and an optical resonator that allows you to keep electromagnetic energy inside for a long time. Perovskite can combine these properties - a cubic nanoparticle is capable of performing both the role of an active medium and the role of a resonator.

As a result, scientists managed to obtain a nanoparticle measuring 310 nanometers, which, when excited by a femtosecond laser, is able to maintain laser generation at room temperature.

"To pump the nanolaser, we used femtosecond laser pulses and irradiate a single nanoparticle with them in a microscope until at a certain intensity we overcome the threshold of laser generation. Then the nanoparticle begins to work precisely as a full-fledged laser. We have shown that such a laser works for at least millions of acts of pumping with external pulses, " noted Ekaterina Tiguntseva, co-author of the work as a junior researcher at ITMO University

The peculiarity of the obtained nanolaser lies not only in its size. The point is also how well it retains the energy of forced radiation in itself in order to ensure sufficient amplification of electromagnetic fields for the appearance of laser generation.

"The whole idea is that laser generation is a threshold process, that is, you shine an external laser on a particle, and at some certain," threshold, "intensity of the external source, the particle itself begins to generate laser radiation. If the light is very poorly held inside, then no matter how much you shine, you will never get laser generation. In previous works with other materials and systems, but similar ideas, it was shown that it is possible to use Mi resonances of the fourth and fifth orders - this means that the wavelength in the material was laid inside the resonator four or five times, at the frequency of laser generation. We showed that our particle emits on the resonance of the Mi of the third order. In other words, we can achieve coherent forced radiation if the wavelength in the perovskite fits inside the particle only three times, " noted Kirill Koshelev, co-author of the work as a junior researcher at ITMO University

The nanoparticle does not work as a laser at any particular pressure or extremely low temperature. All the effects described were observed at standard atmospheric pressure and room temperature. This can attract specialists who are engaged in the creation of optical chips, sensors and other devices that use light to transmit and process information. This can also be used to create chips for an optical computer.

A feature of lasers operating in the visible range is that they, all other things being equal, are smaller than red and infrared emitters of similar characteristics. The size of the emitter is cubically dependent on the wavelength of the radiation, and since the wavelength of green light is three times smaller than infrared, the limit level of miniaturization also extends further for green nanolasers. This is important for creating compact components for future optical computing systems.

See also

• Semiconductor lasers

• Semiconductors (Global Market)
• Semiconductors (China Market)
• Semiconductors (US market)

• Laser Equipment (Lasers) (Russian Market)