Author: Dr. Mindaugas Karaliūnas

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Lithuanian patent “Broadband high-frequency generating / amplifying device, using semiconductor superlattices” by Gintaras Valušis, Kirill Alekseev, Vladislovas Čižas, Linas Minkevičius, Natalia Alexxeva, Dalius Seliuta, Liudvikas Subačius ( LT2021567).

New principle and at the same time a new type of compact high-frequency radiation source operating at room temperature that can be placed on a semiconductor chip is suggested. It is broadband and can operate in the both GHz and THz frequency bands. Operation of the device relies on principles of the quantum optoelectronics (Esaki-Tsu nonlinearity of the quantum super-lattice), and employ drift-relaxation modes to amplify high-frequency radiation, which propagates in a semiconductor superlattice along its axis at a speed approximately 1000 times slower than the speed of light in a material. It can be realized in semiconductor superlattice with non-ohmic injection contacts of an appropriate design.

Patent No. LT2021567. At the time of writing this post some public access restrictions were implemented on this patent.

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High precision parabolic quantum wells grown using pulsed analog alloy grading technique: Photoluminescence probing and fractional-dimensional space approach

New paper by M. Karaliūnas et al. “High precision parabolic quantum wells grown using pulsed analog alloy grading technique: Photoluminescence probing and fractional-dimensional space approach” reports the findings on PL characterization with the help of fractional-dimensional space approach revealed precisely grown parabolic quantum well using molecular beam epitaxy pulsed analog alloy grading technique. The study presents beautiful physics of electrons being confined in 52-nm-width parabolic quantum well and proves the validity of Khon theorem. The work was supported by European Social Fund (project No 09.3.3-LMT-K-712-02-0172) under grant agreement with the Research Council of Lithuania (LMTLT). It can be reached via DOI: 10.1016/j.jlumin.2021.118321

 

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Review: Roadmap of Terahertz Imaging 2021

Impressive review by G. Valušis et al. is published in Sensors (MDPI) journal. The roadmap article is focused on the most recent advances in THz imaging with particular attention paid to the optimization and miniaturization of the THz imaging system. Although the research on preparing the review haven’t received dedicated funding, the work covers the results of number of grants: Deutsche Forschungsgemeinschaft, contracts RO 770/40, /43 and /48, ME5034/2; Messer Stiftung, project “Orts- und zeitaufgelöste Spektroskopie an plasmonischen Strukturen mittels s-SNOM-Nanoskopie”, IRAP Programme of the Foundation for Polish Science (grant MAB/2018/9, project CENTERA), project KITKAS, founded by Lithuanian Research Council, LAT-04/2016. The work is accessible via DOI: 10.3390/s21124092

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New Study on Antenna-Coupled Titanium Microbolometers

Newest study “Antenna-Coupled Titanium Microbolometers: Application for Precise Control of Radiation Patterns in Terahertz Time-Domain Systems” is published in Sensors journal from MDPI publisher. It was found that the studied Ti-microbolometers are convenient lensless sensors suitable to discriminate and control THz radiation pattern features in various wideband THz-TDS systems. The publication is open access and can be found through DOI: https://doi.org/10.3390/s21103510

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New work by V. Janonis et al. is published in Optics Express

Most recent study by V. Janonis and co-authors “Spatial coherence of hybrid surface plasmon-phonon-polaritons in shallow n-GaN surface-relief gratings” is published in the highly ranked Optics Express journal from Optical Society of America (OSA) Publishing. Good agreement was achieved between experiment and theory paving a way for development of narrow-band thermal sources of coherent radiation in IR and THz ranges. The work was funded by the European Regional Development Fund according to the supported activity “Research Projects Implemented by World-class Researcher Groups” under the Measure No. 01.2.2-LMT-K-718-0047 through the Research Council of Lithuania (Lietuvos mokslo taryba) grant the “KOTERA-PLAZA” Project (No. DOTSUT-247).  Note, that this publication is Open Access and can be reached through this link:

https://doi.org/10.1364/OE.423397

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Laser Micromachining Technology for AlGaN/GaN HEMTs and Schottky barrier diodes

Recent study “Laser Processing of Transparent Wafers with a AlGaN/GaN Heterostructures and High-Electron Mobility Devices on a Backside” was published by S. Indrašiūnas et al. in “Micromachines” Journal from MDPI publisher. In the thorough study laser ablation process was optimized and used to dice transparent wafers with AlGaN/GaN heterostructures with various electronic devices. The work was supported from the Research Council of Lithuania (Lietuvos mokslo taryba) through the “T-HP” Project (Grant No. DOTSUT-184) funded by the European Regional Development Fund according to the supported activity “Research Projects Implemented by World-class Researcher Groups” under the Measure No. 01.2.2-LMT-K-718-03-0096. The work can be reached through DOI: https://doi.org/10.3390/mi11121131