ITMO: Nanodevice for optical computer

The main articles are:

• Optical computers
• Semiconductor materials

2023: Developing a Nanodevice for an Optical Computer

Physicists of ITMO and the Academic University named after Zh.I. Alferov have developed a device that can be used as a transistor for an optical computer. The development allows without the use of electrical conductors to create an electric field in a nanostructure. Scientists were able not only to theoretically describe this process, but also to experimentally demonstrate it in a nanoantenne. The results of the study are published in the journal Light: Science & Applications. This was reported on September 21, 2023 in ITMO.

Transistors, tiny semiconductor devices that are needed to control the electronic flow containing information, are becoming smaller and more energy efficient every year. In many ways, the power and speed of any equipment, including computers and smartphones, depends on them. However, scientists and engineers have almost reached fundamental limits for improving them. You can increase the performance of devices by switching from electrons to particles of light (photons). Photons are an ideal tool for transmitting information: light can be transported for tens and hundreds of kilometers with virtually no attenuation or distortion. Therefore, the creation of an optical computer has long been not just a scientific interest, but a necessity.

To develop an optical computer, you need to replace each part of a regular PC with an optical analogue. We were able to make in some ways the building brick of the future optical chip - a nanostructure that can be used as a capacitor or even a transistor. With its help, you can also control the flow of photons: for example, change the intensity or direction of radiation. Also, in our nanostructure, it was possible to generate a constant electric field - and only due to light, without the use of electrodes or additional electrical systems, narrated by Yali Sun, first author of the paper, Associate Research Fellow, ITMO Faculty of Physics.

Miniaturization is another task that scientists tried to solve: the smaller the structure, the more potential transistors can be placed on a unit area, that is, the more powerful the ready-made device will be. The presence of optical resonance properties and the combination of two materials in a single nanosystem allowed scientists to create a static electric field in it under the influence of laser radiation and thus do without electrodes. Previously, this effect could only be demonstrated in bulky systems - for example, in bulk silicon.

In shape, our nanostructure resembles a chess pawn - a sphere immersed in a truncated cone. Our studies on nanostructures with different geometries have shown that this is the shape best suited for generating an electric field. The nanostructure includes materials that are widely used in microelectronics - silicon and gold. How it works: We shine a laser on it and form an electric field in the semiconductor that changes the optical response of the nanosystem. That is, the output of such a nanostructure can be controlled by light. This is important for photon-photon interaction. The results will help in creating optical computers, where all processes will be carried out only at the expense of photons, explained Artem Larin, co-author of the project, engineer of the Physics Department of ITMO.

The most difficult thing in the study was to describe the experimental results by theoretical calculations, since the theory explains the ideal case without taking into account many factors. Further, physicists plan to experiment with other geometries in order to simplify the technology for creating such nanosystems, added Dmitry Zuev, Project Supervisor, Senior Researcher, ITMO Faculty of Physics.