Publications

During the course of the project, the following papers have been published:

6. «High Temperature Operation and Spectral Stability of InGaN/GaN Ring Microlasers on Silicon» (2026), a paper by an international team of authors Kryzhanovskaya N.V. et al., published in the journal IEEE Photonics Technology Letters

Microring lasers with an active region based on InGaN/GaN quantum wells grown on a silicon substrate were investigated. These microlasers are compact in size (6–10 μm) and exhibit lasing in the blue spectral range under optical pumping. For microlasers of this type, the thermal stability of the emission characteristics was studied for the first time. It is shown that lasing is maintained at elevated temperatures up to 100 °C, while the lasing wavelength changes by less than 1 nm. The threshold optical pump power density for lasing is about 220 kW/cm² at room temperature and increases to about 350 kW/cm² when the microlaser is heated to 100 °C.

DOI: 10.1109/LPT.2025.3628068

5. «Optical properties of disk microresonators based on wide-bandgap III-N materials» (2025), a paper by an international team of authors S.D. Komarov et al., published in the journal St. Petersburg Polytechnic University Journal: Physics and Mathematics

The optical properties of III-N disk microresonators with InGaN/GaN quantum wells fabricated on a sapphire substrate were investigated. It is shown that the integrated emission intensity of the quantum wells increases linearly with pump power, indicating the high optical quality of both the epitaxial structures used and the fabricated microresonators. The photoluminescence spectra of the microresonators exhibit a series of local intensity maxima, the spacing between which corresponds to the free spectral range of whispering gallery modes, pointing to the high quality factor of the fabricated microresonators. Despite this, lasing was not achieved in the studied microdisks because of strong mode leakage into the buffer layer. Further optimization of vertical optical confinement is considered a key step toward the development of nitride-based microdisk lasers on sapphire using similar heterostructures.

DOI: 10.18721/JPM.183.142

4. «Investigation of microdisks lasers with an InGaN/GaN quantum well in the active region at elevated temperatures» (2025), a paper by an international team of authors D.A. Masyutin et al., published in the journal St. Petersburg Polytechnic University Journal: Physics and Mathematics

This work investigates the operational stability of microdisk lasers with an active region based on InGaN/GaN quantum wells as the temperature increases from 25 to 100 °C. It is shown that lasing in such devices is maintained throughout the entire temperature range studied: the threshold power changes only slightly, remaining within 245–255 μW, while the lasing wavelength shifts by only 2 nm, from 413 to 415 nm. These results confirm the high thermal stability of InGaN/GaN microdisk lasers and their promise for integration with silicon photonics devices.

DOI: 10.18721/JPM.183.123

3. «Lasing in the InGaN/GaN/AlGaN disk microstructures on silicon» (2025), a paper by an international team of authors E.I. Moiseev et al., published in the journal Technical Physics Letters

The work demonstrates lasing in InGaN/GaN/AlGaN microdisk resonators fabricated on a silicon substrate. In the compact optical microlasers created in this study, with diameters of 5–8 μm, room-temperature lasing was achieved with a threshold pump power density of ~1.4 MW/cm². This became possible due to the use of stepped AlN/AlGaN buffer layers, which provide efficient optical confinement of the active region (Γ ~4.2%) and high crystalline quality of the epitaxial layers in the structure. The study also demonstrates that lasing occurs on whispering gallery modes, and that the lasing wavelength shifts from 406 to 425 nm as the laser diameter increases because of reduced optical losses.

DOI: 10.61011/TPL.2025.06.61288.20298

2. «Mode leakage into substrate in microdisk lasers» (2024), a paper by a team of authors Melnichenko I.A. et al., published in the journal St. Petersburg State Polytechnical University Journal: Physics and Mathematics

Experiment and modelling were used to study leakage of whispering-gallery modes from a quantum-dot injection microdisk laser into a GaAs substrate. For a 50 µm-diameter device with 1.5 µm-thick Al_0.4Ga_0.6As claddings, the leaked-mode intensity can reach ~10^-3 of that inside the waveguide.

DOI: 10.18721/JPM.173.242

1. «Output Power of III-V Injection Microdisk and Microring Lasers» (2025), a paper by an international team of authors Kryzhanovskaya N.V. et al., published in the journal IEEE Journal of Selected Topics in Quantum Electronics

The article discusses lasers based on whispering gallery modes (WGMs). These devices are of interest not only because of their small size, but also because of their high sensitivity to the refractive index of the surrounding medium, which makes it possible to create microlaser-based sensors and also opens up opportunities for the study of quantum chaos. However, low output coupling losses in high-Q resonators may negate the practical advantages of the laser. This review summarizes published data on the achieved output optical power in various III-V injection microlasers and analyzes the key factors limiting the maximum output power, in particular the influence of active-region self-heating during continuous-wave operation and the difficulty of light extraction from WGM-based resonators. Different III-V materials and fabrication methods developed to improve the output power of WGM microlasers were also compared.

DOI: 10.1109/JSTQE.2024.3450812