2020: ITMO scientists have proposed a planar platform for creating an optical transistor
On April 10, 2020, ITMO reported that leading scientific teams in the field of nanophotonics are working to create optical transistors that will form the basis of an optical computer. The transmission of information in such devices will be carried out not with the help of electrons, but with the help of photons, which will reduce heating and increase speed. However, there is a difficulty - photons do not interact very well with each other, which adds problems to microelectronics. A group of researchers, based on employees of ITMO University, proposed their own solution to the problem, creating a planar system in which photons bind to other particles and thereby can interact. The principle presented during the experiment can become a platform for creating an optical transistor. The article is published in the journal Light: Science & Applications.
As noted in ITMO, transistors, without which it is impossible to imagine modern human civilization, work due to the controlled movement of electrons along them. This method has been used for decades, but it has a number of drawbacks: firstly, electronics warm during operation, and part of the energy is spent not on useful work, but on parasitic heating. To combat this heating, you have to equip the devices with fans, that is, spend even more energy. Secondly, the speed of electronic devices has its limitations. Some of these problems can be solved by using light particles - photons instead of electrons. Devices in which light can be used to encode information will be less heated, consume less energy and work faster.
That is why the problem of creating optical computers is being dealt with around the world. However, the problem is that photons, unlike electrons, do not interact with each other. Scientists from around the world offer different ways to "train" photons to interact with each other. One such method is to bind photons to other particles. A group of scientists, including employees of the New Phystech of ITMO University, have proposed another effective implementation, where photons bind to excitons in single-layer semiconductors. Excitons occur when an electron excited by external influence reserves a blank valence bond, which physicists call a hole. In this case, the electron and the hole can bind to each other, forming a new particle - an exciton, which can interact with the same particles.
 | "If the exciton is bound to light particles, then we get the polariton. This particle will be partly light, with which it will be possible to quickly transmit information, and at the same time it will be able to interact with other same particles, " noted' Vasily Kravtsov, co-author, leading researcher at ITMO University |  |
It would seem that polaritons solve the problem: you just need to create a transistor based on them. However, everything is not so simple - it is necessary to create a system in which such particles would exist for a long time and at the same time have high interaction rates. In the laboratories of the New Fizteh of ITMO University, polaritons are obtained using a laser, a waveguide and the thinnest layer of a semiconductor. A semiconductor plate with a thickness of only three atoms is placed on a waveguide created from optical material, on the surface of which a mesh of the thinnest grooves is specially cut. After that, a red laser shines on this system, which creates excitons in the semiconductor, which in turn bind to light particles, forming polaritons.
The resulting polaritons not only exist for a relatively long time, but also have high non-linearity indicators, that is, they actively interact with each other.
| | "This brings us a step closer to creating an optical transistor - we have a planar platform that can be integrated into a chip less than 100 nanometers thick. Since particle interaction rates are large, we don't need to install a powerful laser, a small enough red light source that can also be integrated on the chip, " noted' Vasily Kravtsov, co-author, leading researcher at ITMO University | |
According to April 2020, scientists continue experiments. They are faced with the task of showing that the system works at room temperature.
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