Faster communications, 6G technologies, security systems, new semiconductor materials, semiconductor chips, quantum innovations - world-renowned scientists and innovators will be discussing these and other topics.

 

Optoelectronics is a field of science and technology that studies the interaction between light and semiconductors. The most popular example of semiconductors and optoelectronics is your smartphone, which has many chips and circuits, a touchscreen, the ability to take photos and videos, record sounds... But optoelectronics covers a much broader field of topics.

 

The main organiser of APROPOS 19, physicist Prof. Dr. habil. Gintaras Valušis, Head of the Department of Optoelectronics at the FTMC, talks about the event and the current world technology trends.

 

 

 

Vilnius has always been associated with semiconductor research, and PFI has been one of the world's leading institutions in this field. That's where it all started.

 

Over the years, the themes of the conference have evolved, and today, optoelectronic materials and semiconductors are taking on a new lease of life because of their relevance, but from a different perspective. So the aim of our event is to bring together, to listen to the global stars of the field, the leading scientists, to hear what they think, what they have developed, what they have researched - and what they see as the future prospects for semiconductors, optoelectronics and new devices in research, applications and, of course, industrialisation.

 

 

A few years ago, there was a popular perception that when the smartphone (which is essentially an integrated piece of semiconductors and the chips, variously engineered and technologically processed) was created, it seemed that there was nothing left: the possibilities of silicon were so clear and the technology so good and cheap that there was hardly anything else to invent.

 

But now, with the very pressing issues of connectivity and security, silicon is no longer enough. Simple electronics are fine, but higher powers are needed, and the new generations of communications also require longer distances and higher frequencies. Here too, silicon has its limits, its capabilities are no longer sufficient.

 

This requires both new materials and solutions. The ability to put a lot into a relatively small thing to make it work. Sometimes it's very difficult: individual things work, but when you put them together, somehow they don't - or don't work as well as we would like. This is called hybrid, or heterogeneous, integration, depending on what we're trying to connect - separate pieces of circuitry or trying to combine two different materials on a semiconductor chip.

 

And it's not the same as spreading butter on bread, where everything usually "sticks" well, popularly speaking. Here we are talking about technological "sandwiches" at the level of atomic-sized layers, where the sensitivity to adhesion is incomparably higher than that of a simple sandwich! Not only do the layers need to be adhesive and defect-free, the electrons need to be able to travel fast and not bump into barriers or defects that severely limit the frequency and quality of the devices.

 

 

 

 

Terahertz uses frequencies a thousand times higher than a mobile phone. The first wave of terahertz was related to security systems. How can I see inside an envelope without opening it? Since terahertz has the ability to propagate through dielectric materials - packaging, paper, clothing - it is possible to identify objects inside. Tell if they are dangerous, etc. Hence the relevance of terahertz imaging and terahertz spectroscopy.

 

Today, we know how to build security systems, and there is a wealth of research on imaging. Now a new hot topic has emerged: communication systems. We are using 5G technologies and we say that it is very good. But people in science are already talking about 6G and 7G! These are about even higher frequencies, even higher information flows, expanded sensor capabilities. We need higher power, new materials and new engineering - and terahertz is becoming very important.

 

Here we face challenges. Water is highly absorbent to terahertz - so rain would severely hamper the quality of this connection. Making a terahertz connection at any frequency would be difficult, so we need to choose a specific frequency and a way to direct the radiation so that the system works effectively, even in rainy weather. There are more interrelated problems that we have to deal with.

 

The other side of the issue is the availability of terahertz in medicine. Here we still often use X-rays, but the X-ray particle, the photon, is very high-energy, while the terahertz quantum is very small. In addition, unlike X-rays, terahertz radiation is not harmful to us, it is not ionising, so many times it can be used to illuminate, say, the fusion of an implant to bone, and nothing bad happens.

 

At the FTMC, we have a wide range of activities dedicated to these themes - we are trying to develop different measurement methods and solutions for sensors, optical elements and amplifiers.

 

As I said, the topic of security is being revived, where terahertz is an important tool for identifying hazardous materials.

 

 

 

 

I would like to start with Iwao Hosako from the National Institute of Informatics and Communications. This is the institution that is curating the development of new generations of wireless communications in Japan.

 

French researcher Guillaume Ducournau, one of the leaders in the development of 6G in Europe, will talk about how this technology is being developed in different parts of the world.

 

Xavier Rottenberg is one of the leading people at IMEC. IMEC is the leading chip development institution in Europe, a prestigious Belgian institute, similar in style to our FTMC, but more industrial. The guest will tell us what trends are taking place in this institute and what are the prevailing trends in chip development.

 

We will also have Andy Monkman from the UK, one of the world's brightest stars in organic optoelectronics. He is developing new materials for organic light emitting diodes (OLEDs). Take a Samsung or Apple phone: many of their displays are made of organic semiconductors. So it is Mr. Monkman who is one of the leaders in this field.

 

Wojciech Knap, a colleague from Warsaw and one of the leading figures in terahertz physics, will also be attending the conference. He will talk about plasmonic crystals in two-dimensional gases.

 

Agnieszka Siemion, a renowned physicist, will also speak on compact optics for terahertz devices.

 

We will have Saulius Marcinkevičius, a former PFI employee and currently a professor at KTH, the largest technical university in Sweden. He will talk about new semiconductor materials, which is the result of work carried out in collaboration with the group of Nobel laureate Shuji Nakamura (Nakamura received the physics prize for the discovery of LEDs).

 

There will be Wladislaw Michailow from Cambridge, who will talk about new trends in terahertz photonics, and many other people who are pushing optoelectronics and terahertz science forward.

 

 

 

 

It certainly is. He will talk about single photon sources and their use in quantum technology. Radek Łapkiewiz from Poland will give us a presentation on quantum detection, and other eminent personalities will be present.

 

The topic of quantum technologies in Lithuania started partly in the FTMC Department of Optoelextronics and partly at Vilnius University. We have joint activities in this field.  

 

So we will have a lot of famous people. We hope they will help us to enjoy physics for ourselves, to rediscover how beautiful and amazing it can be. On the other hand, as Lithuanians, we also want to make our own contribution and understanding. We will have common interests with Japanese researcher Safumi Suzuki, a world leader in the development and research of resonant tunneling diodes. Our common interests are based on the fact that we are also developing quantum semiconductor structures - but different, called superlattices - which have unique electron transport control properties in the terahertz range.

 

We are happy to be seen in the world, because these stars of science don't go anywhere, and it is not easy to get them to come. Vilnius is a world city of excellence in optoelectronics, semiconductor and terahertz physics. We are happy to contribute to this and proud to organise such a significant event as APROPOS.

 

 

 

 

In this section, we present the joint work of the Lithuanian and Polish research groups, and the most notable publications resulting from their joint work. In this way, we aim to strengthen cooperation between the two countries. Moreover, we also have a historical moment - we want to highlight the positive achievements of the Polish–Lithuanian Commonwealth. And to tell the physics community about it.

 

At the last APROPOS conference in 2022, Prof. Rimvydas Petrauskas, the rector of Vilnius University, gave a very interesting talk about the Union of Lublin. Everybody enjoyed it very much, so we decided to continue the tradition. This time we will have a lecture on the Constitution of May 3rd by Dr. Martynas Jakulis, a historian at Vilnius University.

 

We believe that physicists need to be educated in more than just their day-to-day work. We hope it will be interesting!

 

As for other "non-traditional" areas, we are very pleased that the Lublin Readings will be crowned by a concert of the Chamber Choir Aidija on 2 October, which we are sure the audience will enjoy very much. We invite all Vilnius residents, not only physicists, to attend the concert. After all, physics and music have a lot in common and are inspiring in many ways!