Augustė Černeckytė, an engineer from the Solid-State Lasers Laboratory of the FTMC Department of Laser Technologies, has received an award from the scientific journal Applied Sciences and a cash prize for the best oral presentation in the laser section.

 

Congratulations to our colleague, we are very happy!

 

 

 

"Augustė never ceases to amaze us," says Dr. Aleksej Rodin, Head of the FTMC Solid-State Lasers Laboratory. - This is not her first award, as the previous one was presented at the Open Readings 2023 conference for young scientists. However, this is her first success on the international stage, where Augustė, as the youngest participant, was competing with both PhD students and experienced researchers from around the world working in the field of optics and lasers."

 

The young physicist's field of research is ultrashort pulse lasers. This description is very apt, as her presentation focused on the broadening of the spectrum of a picosecond (one-trillionth of a second!) with a wavelength of 1 micrometre (one-thousandth of a millimetre) laser in hydrogen by applying a non-linear phenomenon called stimulated rotational Raman scattering (SRS).

 

What is it?

 

 

 

"Broadening the spectrum of the laser is important for a wide range of applications: shorter light pulse durations can be achieved with a broader spectrum, while ultrashort lasers at longer wavelengths can be used to generate attoseconds, terahertz generation or particle acceleration," says Augustė. As a reminder, in 2023, three European scientists won the Nobel Prize in Physics for the development of attosecond lasers, and you can fit a quintillion (one with 18 zeros) attoseconds into one second!

 

"Although stimulated Raman scattering was observed more than 60 years ago, it is still interesting today, and not everything has been explored yet. In our study, we were able to achieve a 52% rotational SRS replacement efficiency. In contrast, the conversion efficiency of the widely used technology OPCPA (Optical Parametric Chirped-Pulse Amplification) is typically only about 15%.

 

The near-infrared (IR) spectrum obtained in the study is broad, and the broader the spectrum, the shorter the laser pulse duration can be. Our spectrum has compression prospects as short as 14 femtoseconds (a femtosecond is one thousand trillion times shorter than a second)! Why is this important? Because laser engineers around the world are currently interested in different ways to efficiently achieve pulse durations shorter than 20 femtoseconds.

 

However, as I mentioned, it is more relevant at the moment to reach short impulses at a more distant part of the spectrum. So that's what we are doing now - combining the already mentioned SRS phenomenon with OPCPA technology to achieve longer wavelengths already in the mid-IR spectrum, up to 3.5 micrometres (by the way, the human eye can only see up to 0.7 micrometres)," says the FTMC engineer.

 

 

 

A. Černeckytė, who graduated in January this year, together with her colleagues from the FTMC Solid-State Lasers Laboratory, has already published 2 scientific papers in high-level international journals and 14 conference theses. In her spare time, she enjoys horseback riding and playing the piano and organ.

 

Augustė's supervisors are Dr. Aleksej Rodin and Dr. Paulius Mackonis. Together with her colleagues, the physicist plans to continue her research and achieve unprecedented peak powers:

 

"Peak power is the maximum instantaneous power the laser achieves during the pulse. We aim for terawatt (TW) powers. To help you understand what TW power is, we can use an example: a typical laser pointer (the ones in the tip of a pen) has a power of milliwatts (mW). At that time, terawatts are a trillion times more."

 

 

 

The work of the young scientist is carried out in the Research Council of Lithuania research group project TERRA. Its aim is to investigate advanced multi-optical cycle mid-IR laser architectures, i.e. ultra-short pulse lasers with wavelengths of more than 2 micrometres.

 

Multi-optical-cycle, high-energy, tunable lasers are widely used in ultrafast and high-field physics. Of great interest is their use in the generation of secondary radiation sources such as terahertz (THz) radiation or attosecond X-rays. By increasing the wavelength of the laser radiation, it is possible to improve the efficiency of THz generation or to generate higher photon energy attosecond X-ray pulses.

 

Another relevant advantage of this technology is that the filamentation of intense laser pulses in the air opens up unprecedented possibilities for remote gas detection (which could be particularly useful in the battlefield).

 

"Filamentation of laser pulses in air is an optical phenomenon where an intense laser beam travels through the air and maintains its high intensity over a long distance without significant propagation. Filamentation can be used for remote detection of pollutants and gases due to its high intensity and long propagation distance," explains the FTMC laser specialist.

 

 

 

Research into various non-linear optical phenomena has allowed the Solid-State Lasers Laboratory research team to push to around 2.3 micrometres and achieve multi-millisecond pulses of 25 femtoseconds.

 

The work of our colleagues has demonstrated the advantages of the new method for generating intense mid-IR radiation: one can eliminate phase aligment and the limitations of optical damage in parametric crystals. "As the laser spectrum is significantly broadened, this method is also attractive for achieving efficient pulse compression - laser pulses can be compressed down to a few femtoseconds," says Černeckytė.

 

In order to generate intense femtosecond laser pulses in the mid-IR region, techniques such as hybrid parametrics and stimulated Raman scattering schemes are being further investigated in the laboratory.