New paper about structured THz radiation: Imaging with Airy beam

New paper by Rusnė Ivaškevičiūtė-Povilauskienė et. al just published in Light Science and Applications journal by Nature publishing group entitled ”Terahertz structured light: nonparaxial Airy imaging using silicon diffractive optics”. The work demonstrates the structured nonparaxial THz light in the form of Airy, Bessel, and Gaussian beams generated in a compact way using exclusively silicon diffractive optics prepared by femtosecond laser ablation technology. The structured THz light consistently outperforms the conventional one in resolution and contrast.

The findings open new frontiers of structured light applications in imaging and inverse scattering problems. Imaging of stacked graphene layers with THz Airy beam revealed potential to be applied for inspection of 2D materials quality.

The article is freely available under Open Access license and can be reached through the DOI address:

New study on formation and drift of space-charge domains with velocity of sound in n-type GaN

New paper by Roman Balagula et al. under the title ”Space-charge domains in n-type GaN epilayers under pulsed electric field” is published in the Applied Physics Letters.

The experimental work investigates the formation and drift of space-charge domains with velocity of sound in n-type GaN. The findings defines the constraints
for the design of GaN-based power electronic devices.

The paper can be reached through this DOI:

Dissipative Parametric Gain in a GaAs/AlGaAs Superlattice in PHYSICAL REVIEW LETTERS

New study is published in the journal “Physical Review Letters” from American Physical Society in the field of parametric generation of EM oscillations in GHz-THz frequency range. The work reports on the first observation of the dissipative parametric generation in a subcritically doped GaAs/AlGaAs superlattice (SL) subjected to a DC bias and a microwave pump. It enforces excitation of slow electrostatic waves in the SL that provide a significant enhancement of the gain coefficient.

The findings foresee the development of a miniature solid-state parametric generators of GHz-THz frequencies operating at room temperature.

Sketch of the parametric generation in the SL device.

DOI: 10.1103/PhysRevLett.128.236802

High-Frequency and High-Power Performance of n-Type GaN Epilayers with Low Electron Density Grown on Native Substrate

The article by Roman M Balagula et al. just published in the journal MDPI Materials. The study is aimed towards the high frequency response properties of the n-type GaN epilayers on a native stubstrates. The results indicate new practical possibilities of the GaN material controlled by an external electric field for the development of novel devices for high-power and high-frequency applications.

The work was supported by European Social Fund (project No 09.3.3-LMT-K-
712-19-0184) under grant agreement with the Research Council of Lithuania (LMT), the National Science Centre (Grant No. UMO-2017/27/L/ST7/03283) and the National Center for Research and Development (Grant No. WPC/20/DefeGaN/2018 and No. TECHMATSTRATEG-III/0003/2019/EnerGaN).

The article is published as a open access and can be accessed freely via DOI:

Development of Quaternary InAlGaN Barrier Layer for High Electron Mobility Transistor Structures

Work by J. Jorudas et al. was recently published in the MDPI Materials journal reporting about the development of high electron mobility transistor structures based on quaternary lattice matched InAlGaN barrier layer.

The thorough study on the morphological, optical and electrical properties of the layers is accomplished aiming towards application for microwave power and terahertz plasmonic devices.

The paper is open access and is available through the link:

The work was supported by the Research Council of Lithuania under the “TERAGANWIRE” project (Grant No. S-LL-19-1), by the National Science Center of Poland (Grant No. 2017/27/L/ST7/03283), by “International Research Agendas” program of the Foundation for Polish Science co-financed by the EU under the European Regional Development Fund (Nos. MAB/2018/9), and partially supported by the Polish National Center for Research and Development through projects No. WPC/20/DefeGaN/2018 and No. TECHMATSTRATEG-III/0003/2019.

New work published concerning advantages of optical modulation in terahertz imaging for study of graphene layers

The newest study was published in Journal of Applied Physics by Rusnė Ivaškevičiūtė-Povilauskienė et al. about the advantages of optical modulation in terahertz imaging for study of graphene layers.

It was demonstrated that optical modulation together with simultaneous terahertz (THz) imaging application enables an increase in contrast by an order of magnitude, thereby illustrating the technique as a convenient contactless tool for characterization of graphene deposited on high-resistivity silicon substrates.

The technique is applied in the development and investigation of graphene-based optical diffractive elements for THz imaging systems.

The work achieved funding from Horizon 2020 program under Grant No. 823728 (DiSetCom) as well as by the Academy of Finland Flagship Programme “Photonics Research and Innovation (PREIN)” (Decision No. 320165).

The paper is open access and can be easily reached through the DOI:

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


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

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: