Greetings from Finland

In August 2025, doctoral student Shiran Levy visited Aspen, Finland, to attend the 50th international IRMMW-THz conference on infrared, millimeter, and Terahertz waves. "The conference focuses on research and development of sources and sensors, components and systems, and a variety of applications ranging from elementary physics through astronomy and plasma, to chemistry, biology, defense tech, and medical sensing," explains Levy. "The goal of the conference is to provide an international stage for knowledge sharing and scientific and technological collaborations, thus advancing our understanding and utilization of this unique spectral field."

Levy, 38, married and mother of three, is in the final year of her doctoral studies. She conducts her research at Dr. Asaf Albo's lab, under his and Dr. Boris Desiatov's supervision. "I research GaN-based quantum cascade lasers for the Terahertz spectrum," she elaborates. "Quantum cascade lasers are special, semiconductor-based lasers comprised of ultra-thin layers that create quantum confinement. Unlike conventional semiconductor lasers, where wavelength is determined by the material's energy gaps, quantum cascade lasers allow for precise wavelength engineering through layer thickness design, thereby enabling emission of wavelengths  within the Terahertz region. This region of frequencies has numerous applications, including spectroscopic sensing and imaging, and quantum cascade lasers are the most efficient sources in this range. Having said that, their key downside is that they require cooling, a fact thatlimiting their portability.. GaN has unique properties that make it suitable for operating at high temperatures. By utilizing these advantages, the goal of this research is to design a device that can work at room temperature, negating the need for external cooling, and thus paving the way for compact, practical Terahertz sources."

Aside from a representative from NOVA, Levy was the only other Israeli at the conference. She presented a poster depicting her research: "I showcased a simulated laser that can reach near-room temperatures," she shares. "Our goal was to design a device with a high probability that possible in order to achieve an experimental device.. There is currently no experimental device based on GaN, testifying to the enormity of the challenge. Our goal was to design a device with the highest likelihood of becoming experimental. This is a significant accomplishment in developing GaN-based quantum devices in the Terahertz range.

In addition, Levy presented a poster on behalf of her colleague, Nathalie Lander Gower, whose pregnancy prevented her from attending the conference. "Nathalie's posters showcased her research that focus  on the temperature performance of GaAs-based quantum cascade lasers. In the first study, the impact of thin AlAs layers in THz QCLs was examined, and it was found that they tend to intermix with AlGaAs, altering the effective composition and thereby influencing the operating frequency and device performance. The second study investigated the effect of doping concentration on temperature performance. Together, these studies highlight the importance of precise optimization of material composition and doping in order to improve the efficiency and robustness of THz QCLs,” says Levy.

The reactions, she says, were outstanding. "I presented the poster on the last night of the conference, I was certain no one would show up – and I ended up talking for two hours straight. There were many questions and plenty of positive comments." Levy wishes to thank Dr. Albo: "I am grateful for Asaf's excellent and close mentoring over the years, for pushing me to academic excellence and urging me to participate in conferences. These events allow us to present our research and the knowledge we've accumulated, gain recognition from colleagues from around the world, and form ties with other members of the community, which has immense value."