Congratulations to our colleague and best wishes for continued innovation boosting at our Center!

 

The main goal of the thesis was to make mid-infrared range laser technology more accessible to industry. The challenge lies in the fact that creating devices that emit light in the mid-infrared range, which spans between 3 and 15 micrometers, is quite difficult. Current lasers are large, bulky, and very expensive. Even smaller devices remain costly because the manufacturing process is done manually, resulting in a very low production yield - only about 10% of the lasers produced meet the required specifications.

 

"Together with my supervisor, Dr. Jan Devenson, for whom I am very grateful, we aimed to improve the quality of these light sources, making them easier to manufacture and reducing errors in the crystal growth process. We explored new molecular beam epitaxy (MBE) growth techniques to grow crystals for these lasers with higher quality and using simpler methods. In this dissertation, we successfully achieved that. We developed a new method that allows the growth of high-quality crystals through more straightforward techniques," says Karolis.

 

 

 

But this was not the only discovery they made. While it is widely known that lasers can be used in the mid-infrared range, there are alternatives such as thermal emitters. They are not coherent light sources like lasers and it is easier to produce them because they do not require crystal processing. However, the current market for thermal emitters still involves complex processing techniques, including extensive use of lithography, making them almost as difficult to manufacture as lasers.

 

"We developed a much simpler design, creating light sources that do not even require electricity - they use heat as their energy source. There is no need for complex systems to build them, just MBE, and no further crystal processing is required. No lithography, no metallization, yet they produce a very distinct, narrow bandwidth emission. We even filed a patent application based on this discovery, which is centered around an exotic phenomenon known as the epsilon-near-zero mode. This effect is achieved by adding very high levels of doping into our semiconductors, which is another key discovery of this thesis.

 

Of course, the work with doping is not yet complete. Further research is needed to determine the maximum level of doping that can be introduced into the materials. Therefore, we have not published these findings yet, and more research is required. Although I left this part out of the dissertation, it's worth mentioning that the devices are operational and highly resistant to environmental challenges. Their emission wavelength is so stable that even with a temperature change of up to 150°C, the wavelength position remains unchanged, " stresses K. Stašys.

 

 

 

According to the physicist, these new thermal emitters could be used for chemical sensing, as conventional methods are not always reliable or specific enough. Currently, different chemicals or gases can be indistinguishable from one another, and more reliable systems are often large, bulky, and extremely expensive. This new technology could enable handheld devices for chemical sensing, potentially benefiting industries such as pharmacology and even medicine.