Russian Scientists Integrate Microdisk Laser and Waveguide on a Single Substrate
A group of Russian scientists led by Professor Natalia Kryzhanovskaya at HSE Campus in St Petersburg has been researching microdisk lasers with an active region based on arsenide quantum dots. For the first time, researchers have successfully developed a microdisk laser coupled with an optical waveguide and a photodetector on a single substrate. This design enables the implementation of a basic photonic circuit on the same substrate as the radiation source (microlaser). In the future, this will help speed up data transfer and reduce equipment weight without compromising quality. The study results have been published in Semiconductors.
The growing demands for higher speed and larger volumes of transmitted information necessitate improvements to current communication methods. Photonic integrated circuits (PICs), which use light to transmit information, operate faster, generate less heat, are more resistant to interference, and consume less energy compared to their electronic counterparts.
However, their effective use requires efficient, compact light sources, such as gallium arsenide (GaAs) microdisk lasers. The length of a conventional Fabry–Perot laser is around 1 mm, while a microdisk laser can be up to 1,000 times smaller. In this study, the laser size was reduced to a diameter of 30 to 40 microns.
Effective directional radiation output is essential for the successful implementation of optical communication in photonic integrated circuits (PICs). Directional radiation can be achieved by optically coupling microlasers with a nearby waveguide. The authors of the paper designed and fabricated both a microlaser and a waveguide from a single epitaxial structure, resulting in reduced size and increased stability.
'Creating microdisk lasers coupled to a waveguide is a challenging task. This process involves developing a thin-film epitaxial structure with a specific composition. In our case, we employed gas-phase epitaxy of metal-organic compounds, a method for layered formation of crystals of different substances on top of one another. Lasers and waveguides were created from the resulting structure. This was made possible thanks to the innovations developed by the Mokerov Institute of Ultra High Frequency Semiconductor Electronics of the Russian Academy of Sciences. All these processes required the use of advanced technology and the efforts of a team of experienced, talented, and qualified specialists,' according to Nikita Fominykh, Junior Research Fellow of the International Laboratory of Quantum Optoelectronics at HSE Campus in St Petersburg.
In addition to radiation sources, radiation receivers are also essential for the operation of PICs. In this work, waveguide photodetectors fulfil this role. Thus, it becomes possible to create an optocoupler that combines a microlaser and a waveguide photodetector with a matching operating wavelength on a single substrate. The photodetector used in the optocoupler measured no more than 90 microns, enabling the creation of a highly compact and energy-efficient optocoupler.
'Microdisk lasers are unique optoelectronic devices. With a size comparable to the diameter of a spider silk thread, they can generate a significant amount of optical power. We have experimentally demonstrated that all optoelectronic components necessary for a photonic integrated circuit—a microdisk laser, a waveguide, and a photodetector—can be fabricated from a single epitaxial heterostructure on the same substrate,' says co-author of the paper Natalia Kryzhanovskaya, Head of the International Laboratory of Quantum Optoelectronics at HSE Campus in St Petersburg.
See also:
AI to Enable Accurate Modelling of Data Storage System Performance
Researchers at the HSE Faculty of Computer Science have developed a new approach to modelling data storage systems based on generative machine learning models. This approach makes it possible to accurately predict the key performance characteristics of such systems under various conditions. Results have been published in the IEEE Access journal.
Researchers Present the Rating of Ideal Life Partner Traits
An international research team surveyed over 10,000 respondents across 43 countries to examine how closely the ideal image of a romantic partner aligns with the actual partners people choose, and how this alignment shapes their romantic satisfaction. Based on the survey, the researchers compiled two ratings—qualities of an ideal life partner and the most valued traits in actual partners. The results have been published in the Journal of Personality and Social Psychology.
Trend-Watching: Radical Innovations in Creative Industries and Artistic Practices
The rapid development of technology, the adaptation of business processes to new economic realities, and changing audience demands require professionals in the creative industries to keep up with current trends and be flexible in their approach to projects. Between April and May 2025, the Institute for Creative Industries Development (ICID) at the HSE Faculty of Creative Industries conducted a trend study within the creative sector.
‘The Fundamental Principle of Scientific Knowledge Is Honesty’
Daria Mazur has wanted to pursue science since she was 13 years old—ever since she discovered in the seventh grade that she was good at physics. In an interview for the HSE Young Scientists project, she spoke about her theoretical research on the electric double layer, speed reading, and the MGMT song ‘Little Dark Age.’
From Neural Networks to Stock Markets: Advancing Computer Science Research at HSE University in Nizhny Novgorod
The International Laboratory of Algorithms and Technologies for Network Analysis (LATNA), established in 2011 at HSE University in Nizhny Novgorod, conducts a wide range of fundamental and applied research, including joint projects with large companies: Sberbank, Yandex, and other leaders of the IT industry. The methods developed by the university's researchers not only enrich science, but also make it possible to improve the work of transport companies and conduct medical and genetic research more successfully. HSE News Service discussed work of the laboratory with its head, Professor Valery Kalyagin.
Children with Autism Process Sounds Differently
For the first time, an international team of researchers—including scientists from the HSE Centre for Language and Brain—combined magnetoencephalography and morphometric analysis in a single experiment to study children with Autism Spectrum Disorder (ASD). The study found that children with autism have more difficulty filtering and processing sounds, particularly in the brain region typically responsible for language comprehension. The study has been published in Cerebral Cortex.
HSE Scientists Discover Method to Convert CO₂ into Fuel Without Expensive Reagents
Researchers at HSE MIEM, in collaboration with Chinese scientists, have developed a catalyst that efficiently converts CO₂ into formic acid. Thanks to carbon coating, it remains stable in acidic environments and functions with minimal potassium, contrary to previous beliefs that high concentrations were necessary. This could lower the cost of CO₂ processing and simplify its industrial application—eg in producing fuel for environmentally friendly transportation. The study has been published in Nature Communications.
HSE Scientists Reveal How Staying at Alma Mater Can Affect Early-Career Researchers
Many early-career scientists continue their academic careers at the same university where they studied, a practice known as academic inbreeding. A researcher at the HSE Institute of Education analysed the impact of academic inbreeding on publication activity in the natural sciences and mathematics. The study found that the impact is ambiguous and depends on various factors, including the university's geographical location, its financial resources, and the state of the regional academic employment market. A paper with the study findings has been published in Research Policy.
Group and Shuffle: Researchers at HSE University and AIRI Accelerate Neural Network Fine-Tuning
Researchers at HSE University and the AIRI Institute have proposed a method for quickly fine-tuning neural networks. Their approach involves processing data in groups and then optimally shuffling these groups to improve their interactions. The method outperforms alternatives in image generation and analysis, as well as in fine-tuning text models, all while requiring less memory and training time. The results have been presented at the NeurIPS 2024 Conference.
When Thoughts Become Movement: How Brain–Computer Interfaces Are Transforming Medicine and Daily Life
At the dawn of the 21st century, humans are increasingly becoming not just observers, but active participants in the technological revolution. Among the breakthroughs with the potential to change the lives of millions, brain–computer interfaces (BCIs)—systems that connect the brain to external devices—hold a special place. These technologies were the focal point of the spring International School ‘A New Generation of Neurointerfaces,’ which took place at HSE University.