Journals >Frontiers of Optoelectronics
Contents
2025
Volume: 18 Issue 1
4 Article(s)
Export citation format
RESEARCH ARTICLE
Laser speckle contrast imaging with principal component and entropy analysis: a novel approach for depth‑independent blood flow assessment
Surkov Yu., Timoshina P., Serebryakova I., Stavtcev D.... and Tuchin V.|Show fewer author(s)
Current study presents an advanced method for improving the visualization of subsurface blood vessels using laser speckle contrast imaging (LSCI), enhanced through principal component analysis (PCA) filtering. By combining LSCI and laser speckle entropy imaging with PCA filtering, the method effectively separates statiCurrent study presents an advanced method for improving the visualization of subsurface blood vessels using laser speckle contrast imaging (LSCI), enhanced through principal component analysis (PCA) filtering. By combining LSCI and laser speckle entropy imaging with PCA filtering, the method effectively separates static and dynamic components of the speckle signal, significantly improving the accuracy of blood flow assessments, even in the presence of static scattering layers located above and below the vessel. Experiments conducted on optical phantoms, with the vessel depths ranging from 0.6 to 2 mm, and in vivo studies on a laboratory mouse ear demonstrate substantial improvements in image contrast and resolution. The method's sensitivity to blood flow velocity within the physiologic range (0.98–19.66 mm/s) is significantly enhanced, while its sensitivity to vessel depth is minimized. These results highlight the method's ability to assess blood flow velocity inde-pendently of vessel depth, overcoming a major limitation of conventional LSCI techniques. The proposed approach holds great potential for non-invasive biomedical imaging, offering improved diagnostic accuracy and contrast in vascular imaging. These findings may be particularly valuable for advancing the use of LSCI in clinical diagnostics and biomedical research, where high precision in blood flow monitoring is essential..
Frontiers of Optoelectronics
- Publication Date: Jan. 03, 2025
- Vol. 18, Issue 1, 1 (2025)
Performance optimization of planar photonic crystal bound states in the continuum cavities: mitigating finite‑size effects
Hao Ran, Ye Bilin, Xu Jinhong, and Zou Yonggang
Bound states in the continuum (BICs) offer a promising solution to achieving high-quality factor (Q factor) cavities. However, finite-size effects severely deteriorate the BIC mode in practical applications. This paper reports the experimental demonstration of an electrically pumped 940 nm laser based on optimized BIC Bound states in the continuum (BICs) offer a promising solution to achieving high-quality factor (Q factor) cavities. However, finite-size effects severely deteriorate the BIC mode in practical applications. This paper reports the experimental demonstration of an electrically pumped 940 nm laser based on optimized BIC cavity, achieving a high Q factor of up to 1.18×104 even with finite photonic crystal footprint, which is two orders of magnitude larger than un-optimized BIC design. Two strategies have been systematically investigated to mitigate finite-size effects: reflective photonic crystal cavity design and graded photonic crystal cavity design. Both methods significantly improve the Q factor, demonstrating the effectiveness of preserving BIC characteristics in finite-sized photonic crystal cavities. In addition, the reflective boundary photonic crystal design is fabricated and experimentally characterized to demonstrate its lasing characteristics. The fabricated laser exhibits single-mode operation with a signal-to-noise ratio of 38.6 dB. These results pave the way for future designs of BICs with finite size in real applications, promoting the performance of BIC-based integrated lasers..
Frontiers of Optoelectronics
- Publication Date: Mar. 14, 2025
- Vol. 18, Issue 1, 3 (2025)
Numerical study of terahertz radiation from N‑polar AlGaN/GaN HEMT under asymmetric boundaries
Xing Runxian, Guo Hongyang, Guo Bohan, Yu Guohao... and Zhang Baoshun|Show fewer author(s)
In this paper, we have studied the electrical excitation of plasma-wave in N-polar AlGaN/GaN high electron mobility transistors (HEMT) under asymmetric boundaries leads to terahertz emission. Numerical calculations are conducted through the simultaneous solution of Maxwell's equations and the self-consistent hydrodIn this paper, we have studied the electrical excitation of plasma-wave in N-polar AlGaN/GaN high electron mobility transistors (HEMT) under asymmetric boundaries leads to terahertz emission. Numerical calculations are conducted through the simultaneous solution of Maxwell's equations and the self-consistent hydrodynamic model. By employing this method, we solved the plasma-wave model in the channel of an N-polar AlGaN/GaN HEMT. We estimate that, under ideal boundary conditions and with sufficient channel mobility, these devices could generate milliwatts of power. The effects of different GaN channel layer thickness, carrier concentration, gate length and channel carrier velocity on plasma wave oscillation and terahertz radiation in N-polar AlGaN/GaN HEMT are considered. These simulation results based on Dyakonov–Shur instability provide guidance for the future design of high-radiation-power on-chip terahertz sources based on N-polar AlGaN/GaN HEMTs..
Frontiers of Optoelectronics
- Publication Date: Mar. 14, 2025
- Vol. 18, Issue 1, 4 (2025)
REVIEW ARTICLE
Effect of terahertz radiation on cells and cellular structures
Rytik A. P., and Tuchin V. V.
The paper presents the results of modern research on the effects of electromagnetic terahertz radiation in the frequency range 0.5–100 THz at different levels of power density and exposure time on the viability of normal and cancer cells. As an accompanying tool for monitoring the effect of radiation on biological cellThe paper presents the results of modern research on the effects of electromagnetic terahertz radiation in the frequency range 0.5–100 THz at different levels of power density and exposure time on the viability of normal and cancer cells. As an accompanying tool for monitoring the effect of radiation on biological cells and tissues, spectroscopic research methods in the terahertz frequency range are described, and attention is focused on the possibility of using the spectra of interstitial water as a marker of pathological processes. The problem of the safety of terahertz radiation for the human body from the point of view of its effect on the structures and systems of biological cells is also considered..
Frontiers of Optoelectronics
- Publication Date: Jan. 27, 2025
- Vol. 18, Issue 1, 2 (2025)
© Copyright 2018-2021 | Chinese Laser Press. All Rights Reserved 沪ICP备15018463号-20