capability is critical for holographic near-eye displays. Since most systems employ phase-only spatial light modulators (SLMs), computer-generated holograms (CGHs) must be encoded as phase-only holograms (PoHs). This work presents two approaches for PoH-based CGH generation from plane images: a direct single-step method (D-PoH) and an iterative method (I-PoH). Both utilize the Compact Space-Bandwidth Angular Spectrum (CSW-AS) technique for propagation, which is optimal for wide-angle scenarios. We evaluate their accuracy and zero-padding requirements. Results show that I-PoH provides ahigher quality image, but at the cost of cyclic computations and the requirement of substantially larger zero-padding compared to D-PoH, limiting its efficiency for wide-angle applications. Incontrast, I-PoH achieves a maximum field of view (FoV) of 39 degrees, while D-PoH enables a significantly larger FoV of 54 degrees, for a PC with 64GB RAM. These findings demonstrate the advantage of direct single-step encoding for achieving wide-angle holographic displays.
study presents a Free Space Optical Communication system using InP-based integrated transceivers, demonstrating multichannel transmission capabilities. The system utilizes photonic integrated circuits (PICs) to achieve compact, energy-efficient transceivers suitable for scalable optical communication applications. Successful multi-channel data transmission at rates of up to 10 Gb/s was achieved in both indoor (2 m) and outdoor (up to 10 m) environments. The design incorporates distributed Bragg reflector (DBR) lasers, electroabsorption modulators, and arrayed waveguide grating (AWG) multiplexers. The system showcases high-quality transmission with low bit-error rates (BER <= 10-11) and minimal power penalties.
this work, two series of glasses of the NaF-Al2O3-P2O5 ternary system with the Na3Al2(PO4)2F3 nominal composition, doped with Er3+(1% and 0.5%) and Yb3+ ions, were synthesized by a standard melt-quenching method, and their up-conversion photoluminescence properties were studied. The as-received amorphous materials were excited by the IR laser radiation with a wavelength of 976 nm, and their emission spectra in the visible range were measured. The optical measurements were focused on the up-conversion photoluminescence spectra in the visible range. It was found that stronger up-conversion effects were observed for the series containing 1 wt% Er2O3. In the case of 0.5 wt% Er2O3, the emission response was weaker, comparable with the background noise.
This study presents a fan-in coupler architecture for a four-core fiber, implemented using a single diffractive optical element (DOE). The DOE selectively excites two opposite cores while the remaining ones serve as receiving channels. The DOE was designed using an iterative algorithm, resulting in a computer-generated hologram and fabricated using two-photon polymerization (TPP). Numerical simulations and experimental measurements confirmed correct operation of the concept. The proposed coupler shows strong potential for applications in fiber-optic sensing and optical communications. Full Text: PDF References W. Chen et al., "Applications and Development of Multi-Core Optical Fibers", Photonics 11, 270 (2024). CrossRef J. Sun, W. Huang, A. Lorenz, M. Zeisberger, and M. A. Schmidt, "Tunable metafibers: remote spatial focus control using 3D nanoprinted holograms on dual-core fibers", Light Sci. Appl. 14, 237 (2025). CrossRef M. Khosravi, T. Wieduwilt, M. Zeisberger, A. Lorenz, and M.A. Schmidt, "Advanced remote focus control in multicore meta-fibers through 3D nanoprinted phase-only holograms", Nat. Commun. 16, 507 (2025). CrossRef C. Liu, L. Niu, K. Wang, and J. Liu, "3D-printed diffractive elements induced accelerating terahertz Airy beam", Opt. Express 24, 29342 (2016). CrossRef R.D. Muelas-Hurtado, J.L. Ealo, J.F. Pazos-Ospina, and K. Volke-Sepúlveda, "Generation of multiple vortex beam by means of active diffraction gratings", Appl. Phys. Lett. 112, 084101 (2018). CrossRef P. Komorowski, M. Kurowska, M. Kaluza, P. Czerwińska, P. Zagrajek, and A. Siemion, "Neural Network-Based Design of Two-Focal-Spot Terahertz Diffractive Optical Elements", IEEE Trans. Terahertz Sci. Technol. 14, 228 (2024). CrossRef M. Kaluza, P. Komorowski, M. Surma, A. Nieradka, P. Zagrajek, and A. Siemion, "Advanced diffractive optical elements implementing multiple-input spatial multiplexing of terahertz radiation", Opt. Lasers Eng. 184, 108606 (2025). CrossRef M. Surma, M. Kaluza, P. Komorowski, and A. Siemion, "Segmentation of THz holograms for homogenous illumination", Sci. Rep. 14, 12733 (2024). CrossRef Y. Luo, D. Mengu, N. T. Yardimci, Y. Rivenson, M. Veli, M. Jarrahi, and A. Ozcan, "Design of task-specific optical systems using broadband diffractive neural networks", Light Sci. Appl. 8, 112 (2019). CrossRef A. Siemion, "Terahertz Diffractive Optics—Smart Control over Radiation", J. Infrared Millim. Terahertz Waves 40, 477 (2019). CrossRef J. Suszek et al., "Evaluation of the shadow effect in terahertz kinoform gratings", Opt. Lett. 38, 1464 (2013). CrossRef H. Wang et al., "Two-photon polymerization lithography for imaging optics", Int. J. Extreme Manuf. 6, 042002 (2024). CrossRef H. Wang et al., "Bio-Inspired Semi-Active Safeguarding Design with Enhanced Impact Resistance via Shape Memory Effect", Adv. Funct. Mater. 33, 2214211 (2023). CrossRef O. Yermakov et al., "Fiber-based angular demultiplexer using nanoprinted periodic structures on single-mode multicore fibers", Nat. Commun. 16, 2294 (2025). CrossRef Z. Li et al., "Doughnut beam shaping based on a 3D nanoprinted microlens on fiber tip", Opt. Laser Technol. 167, 109798 (2023). CrossRef M. Kaluza, P. Komorowski, A. Nieradka, P. Zagrajek, and A. Siemion, "Implementing Terahertz Spatial Multiplexing and Frequency Demultiplexing Systems Using Diffractive Optical Elements for 6G Telecommunications Applications", IEEE Trans. Microw. Theory Techn. 73, 6037 (2025). CrossRef M. Sypek, "Light propagation in the Fresnel region. New numerical approach", Opt. Commun. 116, 43 (1995). CrossRef
In this research, we provide the outcomes of spectral calculations and selected characteristics of the NLC homologous series of cyanobiphenyls (nCB) and phenylcyclohexanes (nPCH) within the frequency range of 0.4–7.6 THz. Geometry optimizations, assessments of harmonic frequencies, and calculations of intensity were performed utilizing Scigress – Molecular Modelling Software developed by Fujitsu. The numerical analyses were executed following the standard DFT procedure, employing the B88-LYP functional and DZVP basis sets. The results obtained for the absorption spectra, along with physical parameters such as dielectric permittivity, refractive index, and birefringence, are detailed herein. Notably, we demonstrate that the results align well with the referenced experimental findings. Full Text: PDF References J. Parka, K. Sielezin, "0.3-10.0 THz spectra for chosen liquid crystal molecules - simulation and physical properties", Mol. Cryst. Liq. Cryst., 657, 66 (2017). CrossRef K. Sielezin, R. Kowerdziej, J. Parka, "Simulations of some physical parameters of homologous series of nBT and nCHBT at 0.3-20.0 THz", Liq. Cryst., 1563918, 1 (2018). CrossRef Z. Chen, L. Jiang, H. Ma, "Calculation on frequency and temperature properties of birefringence of nematic liquid crystal 5CB in terahertz band", Chem. Phys. Lett., 645, 205 (2016). CrossRef Z. Chen, Y. Jiang, L. Jiang, H. Ma, "Terahertz absorption spectra and potential energy distribution of liquid crystals", Spectrochim. Acta A Mol. Biomol. Spectrosc. 153, 741 (2016). CrossRef Z. Chen, Y. Jiang, L. Jiang, H. Ma, "Molecular vibration mode assignment of nematic liquid crystal 5CB on Terahertz spectra", Liq. Cryst., 42(7), 947 (2015). CrossRef N. Vieweg, M. A. Celik, S. Zakel, V. Gupta, G. Frenking, M. Koch, "Terahertz Absorption of Nematic Liquid Crystals", J. Infrared Milli Terahertz Waves 35, 478 (2014). CrossRef P. Friebel, D. R. Galimberti, M. Savoini, L. Cattaneo, "Unveiling Low THz Dynamics of Liquid Crystals: Identification of Intermolecular Interaction among Intramolecular Modes", J. Phys. Chem. B 128, 596 (2024). CrossRef Molecular Modelling Software SCIGRESS, Fujitsu Limited, Tokyo, Japan, (2016), DirectLink R. Kowerdziej, L. Jaroszewicz, M. Olifierczuk, J. Parka, "Experimental study on terahertz metamaterial embedded in nematic liquid crystal", Appl. Phys. Lett., 106(9), 092905 (2015). CrossRef M. Olifierczuk, R. Kowerdziej, L. Jaroszewicz, M. Czerwinski, J. Parka, "Numerical analysis of THz metamaterial with high birefringence liquid crystal", Liquid Crystals, 39(6), 739 (2012). CrossRef R. Kowerdziej, T. Stańczyk, J. Parka, "Electromagnetic simulations of tunable terahertz metamaterial infiltrated with highly birefringent nematic liquid crystal", Liquid Crystals, 42(4), 430 (2015). CrossRef J. Parka, S. Kłosowicz, "16th Topical Meeting on the Optics of Liquid Crystals", Phot. Lett. Poland, 7(4), 90 (2015). CrossRef U. Chodorow, J. Parka, O. Chojnowska, "Liquid Crystal Materials in THz Technologies", Phot. Lett. Poland, 4(3), 112 (2015). CrossRef
This paper presents comprehensive practical solutions for reducing light pollution in urban LED lighting systems through two complementary approaches: (1) spectral conversion filters for retrofitting existing 4000 K nominal CCT LED luminaires, and (2) systematic methodology for designing environmentally conscious lighting installations. The conversion filter method achieves nominal CCT reduction from 4000 K to CCT ≤ 2700 K, providing a cost effective alternative to complete infrastructure replacement. Full Text: PDF References I. Fryc, S. Bará, M. Aubé, J.C. Barentine, J. Zamorano, "On the Relation between the Astronomical and Visual Photometric Systems in Specifying the Brightness of the Night Sky for Mesopically Adapted Observers", LEUKOS 18, 447 (2022). CrossRef S. Bará, F. Falchi, Artificial light at night: a global disruptor of the night-time environment, Phil. Trans. R. Soc. B 378, 20220352 (2023). CrossRef I. Fryc, The night sky light pollution created by outdoor luminaires, Przegląd Elektrotechniczny 1, 48 (2017). CrossRef J. Falcón, A. Torriglia, D. Attia, F. Viénot, C. Gronfier, F. Behar-Cohen, C. Martinsons, D. Hicks, Exposure to Artificial Light at Night and the Consequences for Flora, Fauna, and Ecosystems, Front. Neurosci. 14, 602796 (2020). CrossRef R. Supronowicz, I. Fryc, Urban park lighting as a source of botanical light pollution, Photon.Lett.PL 11, 90 (2019). CrossRef K.J. Gaston, J. Bennie, T.W. Davies, J. Hopkins, The ecological impacts of nighttime light pollution: a mechanistic appraisal, Biological Reviews 88, 912 (2013). CrossRef T. Longcore, C. Rich, Ecological light pollution, Frontiers in Ecology and the Environment 2, 191 (2004). CrossRef Arrêté du 27 décembre 2018 relatif à la prévention, à la réduction et à la limitation des nuisances lumineuses, (2018). DirectLink Ministère de la Transition Écologique et Solidaire: Bilan de l'application de l'arrêté du 27 décembre 2018 relatif à la prévention, à la réduction et à la limitation des nuisances lumineuses. Paris 2021, (n.d.). DirectLink Generalitat de Catalunya. Decret 190/2015, de 25 d'agost, de desplegament de la Llei 6/2001, de 31 de maig, d'ordenació ambiental de l'enllumenament per a la protecció del medi nocturn. Diari Oficial de la Generalitat de Catalunya, 2015. DirectLink Jefatura del Estado, Ley 31/1988, de 31 de octubre, sobre Protección de la Calidad Astronómica de los Observatorios del Instituto de Astrofísica de Canarias, 1988. DirectLink Joint Research Centre: Revision of the EU Green Public Procurement Criteria for Road Lighting and Traffic Signals. Technical Report, European Commission, 2019. DirctLink CIE TC 5-28, CIE 150:2017 Guide on the Limitation of the Effects of Obtrusive Light from Outdoor Lighting Installations, 2nd Edition, CrossRef CIE TC 4-56, CIE 234:2019 A Guide to Urban Lighting Masterplanning, CrossRef International Dark Sky Community Program Guidelines, (2018). DirectLink A. Machnowska, S. Kołomański, A. Kotarba, T. Ściężor, Zanieczyszczenie światłem w Polsce. Raport 2023, (2023). DirectLink S. Jost, A. Thorseth, T. Poikonen, P. Blattner, T. Gerloff, A. Kokka, P. Dekker, M. Smid, A. Ferrero, T. Kubarsepp, P. Gal, S. Källberg, A. Klej, G. Brida, T. Reiners, K. Ludwig, M. Schneider, L. Hui, EMPIR 15SIB07 PhotoLED - Database of LED product spectra, (2021) CrossRef ANSI C78.377 American National Standard for Electric Lamps-Specifications for the Chromaticity of Solid State Lighting (SSL) Products, (2024). DirectLink A. Hänel, T. Posch, S.J. Ribas, M. Aubé, D. Duriscoe, A. Jechow, Z. Kollath, D.E. Lolkema, C. Moore, N. Schmidt, H. Spoelstra, G. Wuchterl, C.C.M. Kyba, Measuring night sky brightness: methods and challenges, Journal of Quantitative Spectroscopy and Radiative Transfer 205, 278 (2018). CrossRef T. Esposito, K. Houser, Correlated color temperature is not a suitable proxy for the biological potency of light, Sci Rep 12, 20223 (2022). CrossRef M. Pagliaro, Safe and Truly Ecofriendly LED Lighting, Energy Science & Engineering (2025) ese3.70272. CrossRef EN 13201:2015: Road lighting - Part 2: Performance requirements. European Committee for Standardization, Brussels 2015, DirectLink
Excitation of cholesteric liquid crystal lasers with a large diameter pumping spot is considered. It is shown that the introduction of spatial modulation into the pump beam transfers light emission of the liquid crystal layer from the luminescence mode to the lasing mode. Furthermore, the possibility of dynamic recording of information on a laser optical layer with a thickness of 12µm and an area of about 40mm2 is demonstrated. Full Text: PDF References L. Blinov, R. Bartolino (Eds.), Liquid Crystal Microlasers (Trivandrum, Transworld Research Network 2010). DirectLink H. Coles, S. Morris, "Liquid-crystal lasers", Nature Photonics 10, 676 (2010). CrossRef A. Chanishvili, K. Chubinidze, G. Petriashvili, N. Ponjavidze, Z. Wardosanidze, Ts. Zurabishvili, "Enhanced cone-shaped lasing from cholesteric liquid crystals", Opt. Lett. 49(19), 5515 (2024). CrossRef O. Svelto, Principles of Lasers (Springer, New York 2010). CrossRef Z. Wardosanidze, A. Chanishvili, G. Petriashvili, G. Chilaya, "Cholesteric liquid crystal holographic laser", Opt. Lett. 39(4),1008 (2014). CrossRef
Raman spectroscopy (RS) is an excellent photonic measurement technique that can be extremely useful for characterizing kidney stones. Using RS, we can obtain precise information about the chemical composition and microstructure of the crystals that comprise kidney stones. Therefore, this non-invasive technique makes identifying different types of stones possible. Additionally, Raman spectroscopy supported by electron microscopy (SEM) imaging enables us to relate a given kind of crystal to its morphology. This paper presents the results of ex situ analysis of real samples of an unknown type of human kidney stone using RS and SEM techniques, which led to attempts to identify the stone. Full Text: PDF References P.J.S. Osther, Epidemiology of Kidney Stones in the European Union (Springer London, 2013). CrossRef G. Zeng, Z. Mai, S. Xia, Z. Wang, K. Zhang, L. Wang, Y. Long, J. Ma, Y. Li, S.P. Wan, W. Wu, Y. Liu, Z. Cui, Z. Zhao, J. Qin, T. Zeng, Y. Liu, X. Duan, X. Mai, Z. Yang, Z. Kong, T. Zhang, C. Cai, Y. Shao, Z. Yue, S. Li, J. Ding, S. Tang, Z. Ye, "Prevalence of kidney stones in China: an ultrasonography based cross-sectional study", BJU Int. 120(1), 109 (2017). CrossRef K. Christian, M. Johanna, A. Werner, B. Kathrin, G.M. Tesfay, R.H. Abbas A, W. Stefan, B. Andreas, N.F. Wilhelm, S. Florian, "Raman difference spectroscopy: a non-invasive method for identification of oral squamous cell carcinoma", Biomed Opt. Express 5(9), 3252 (2014). CrossRef C.A. Lieber, H.E. Nethercott, M.H. Kabeer, "Cancer field effects in normal tissues revealed by Raman spectroscopy", Biomed. Opt. Express 1(3), 975 (2010). CrossRef S. Feng, R. Chen, J. Lin, J. Pan, G. Chen, Y. Li, M. Cheng, Z. Huang, J. Chen, H. Zeng, "Nasopharyngeal cancer detection based on blood plasma surface-enhanced Raman spectroscopy and multivariate analysis", Biosens. Bioelectron. 25(11), 2414 (2010). CrossRef X. Cui, Z. Zhao, G. Zhang, S. Chen, Y. Zhao, J. Lu, "Analysis and classification of kidney stones based on Raman spectroscopy", Biomed. Opt. Express 9(9), 4175 (2018). CrossRef Y.-Ch. Hsu, Y.-H. Lin, L.-D. Shiau, "Effects of Various Inhibitors on the Nucleation of Calcium Oxalate in Synthetic Urine", Crystals 10, 333 (2020). CrossRef P. Chatterjee, A. Chakraborty, A. Mukherjee, "Phase composition and morphological characterization of human kidney stones using IR spectroscopy, scanning electron microscopy and X-ray Rietveld analysis", Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy 200, 33 (2018). CrossRef W. Różański, Przegląd Urologiczny 6(58), 34 (2009). DirectLink C. Conti, L. Brambilla, C. Colombo, D. Dellasega, G. Diego Gatta, M. Realini, G. Zerbi, "Stability and transformation mechanism of weddellite nanocrystals studied by X-ray diffraction and infrared spectroscopy", Physical Chemistry Chemical Physics 43, 14560 (2010). CrossRef J. Duława, "Czynniki rozwoju kamicy nerkowej", Forum Nefrologiczne 3, 2, (2009). DirectLink J.W. Robinson, W.W. Roberts, A.J. Matzger, "Kidney stone growth through the lens of Raman mapping", Sci. Rep. 14, 10834 (2024). CrossRef E. Yakubovskaya, T. Zaliznyak, J. Martínez Martínez, et al., "Tear Down the Fluorescent Curtain: A New Fluorescence Suppression Method for Raman Microspectroscopic Analyses", Sci. Rep. 9, 15785 (2019). CrossRef
We analyzed the mechanism of alkali-ions migration taking part in obtaining the frozen ionic potential responsible for the creation of second-order nonlinearity in optical fibers made of silica and other oxide-based glasses. We confirmed that the presence of alkali ions in the oxide glass, together with a high χ(3) value, allows to obtain ionic potential, even though these ions are structural elements of glass rather than impurities. Creation of second-order susceptibility in glass is possible and, depending on alkali-ion concentration, χ(2) can be higher than for a silica-based fiber of the same geometry. Calculated χ(2) reached 0.58 pm/V, and the maximum value obtained for silica-based fiber for the same thermal poling conditions was only 0.33 pm/V. Full Text: PDF References U. Österberg and W. Margulis, "Experimental studies on efficient frequency doubling in glass optical fibers," Opt. Lett. 12(1), 57 (1987) CrossRef H. An and S. Fleming, "Creating second-order nonlinearity in pure synthetic silica optical fibers by thermal poling," Opt. Lett. 32(6), 832 (2007) CrossRef H. An and S. Fleming, "Second-order optical nonlinearity in thermally poled borosilicate glass," Appl. Phys. Lett. 89(18), 181111 (2006) CrossRef W. Margulis, O. Tarasenko, and N. Myrén, "Who needs a cathode? Creating a second-order nonlinearity by charging glass fiber with two anodes," Opt. Express 17(17), 15534 (2009) CrossRef F. De Lucia, D.W. Keefer, C. Corbari, and P.J.A. Sazio, "Thermal poling of silica optical fibers using liquid electrodes," Opt. Lett. 42(1), 69 (2017) CrossRef P. Kabaciński, T.M. Kardaś, Y. Stepanenko, and C. Radzewicz, "Nonlinear refractive index measurement by SPM-induced phase regression," Opt. Express 27(8), 11018 (2019) CrossRef A. Kudlinski, Y. Quiquempois, G. Martinelli, "Modeling of the χ(2) susceptibility time-evolution in thermally poled fused silica," Opt. Express 13(20), 8015 (2005) CrossRef A. Camara, O. Tarasenko, and W. Margulis, "Study of thermally poled fibers with a two-dimensional model," Opt. Express 22(15), 17700 (2014) CrossRef F. Bergmann et al., "Measuring the permittivity of fused silica with planar on-wafer structures up to 325 GHz," Appl. Phys. Lett. 124(7), 072902 (2024) CrossRef Corning Inc., "Datasheet for Corning Pyrex glass," Aug. 13, 2025. DirectLink B. Morova et al., "Fabrication and characterization of large numerical aperture, high-resolution optical fiber bundles based on high-contrast pairs of soft glasses for fluorescence imaging," Opt. Express 27(7), 9502 (2019) CrossRef R.W. Boyd, "The nonlinear optical susceptibility," in Nonlinear Optics, 3rd ed., Academic Press, 2008, 1-67. CrossRef
Dual-frequency liquid crystal (LC) materials for tunable beam steering in the 0.1-3.5 THz range were investigated. Recent LC formulations exhibit a low loss tangent, high polarization coefficients, and significant dielectric and optical anisotropies, including suitably high birefringence for effective THz modulation. We have implemented this material in electrically tunable phase shifters and beam-steering elements, demonstrating their ability to operate with low absorption and controllable birefringence. The obtained characteristics suggest that dual-frequency LCs could be used to create compact, efficient, and highly tunable THz photonic and sensing components. This study outlines the performance parameters relevant to practical THz devices and highlights their potential for reconfigurable photonic architectures.
report on the generation and electric-field stabilization of scalar vortex nematicons in a low-birefringence nematic liquid crystal (LB NLCs). Using mixture 903, we demonstrate self-confined vortex beams that preserve their topological charge and maintain a doughnut-shaped profile over millimetre-scale distances. Utilizing a low-frequency electric field, we show that temporal fluctuations, polarization mixing, and azimuthal distortions are substantially reduced. Interferometric measurements confirm the presence of robust phase singularities, while intensity maps reveal enhanced symmetry and stability as the voltage increases. The combined effects of LB and electric-field-induced fluctuation quenching establish the 903 NLCs mixture as a promising platform for stable vortex spatial solitons and tunable structured-light photonic applications.
(TPV) systems rely on spectrally selective reflectors to enhance conversion efficiency by maximizing photon flux above the photovoltaic bandgap while suppressing subbandgap thermal losses. This work presents a numerical analysis and simulation of SiO2/TiO2 multilayer photonic crystal Distributed Bragg Reflectors (DBRs) tailored to the GaAs bandgap (approximate to 872 nm). The Transfer Matrix Method (TMM) was applied to investigate the optical properties of the structure, taking into account the layer's thickness, number of periods, and refractive index contrast. Investigation demonstrates that an optimized multilayer design exhibits narrowband reflection peaks centered around 800-1000 nm (approximate to approximately 200 nm), closely matching the GaAs photovoltaic cutoff wavelength, with reflectivity exceeding 0.99. Beyond 1000 nm, reflectivity is strongly suppressed, minimizing energy reflections associated with unusable infrared photons. The stability analysis, considering both angular and polarization effects, suggests robust performance over a wide range of angles of incidence, which is a critical requirement for practical and efficient TPV operations. The numerical and simulation findings highlight the potential of SiO2/TiO2 1D photonic crystal thermally stable, tunable selective reflectors, offering a viable pathway for efficiency enhancement in GaAs based TPV systems.
In this paper, we present the results of measurements performed using a Fabry P & eacute;rot resonator printed on a fiber optic tip. Thanks to its design, the resonator allows for simple sputtering of both resonator mirrors with varying degrees of reflection in a single process step. Applying different reflectances to both resonator mirrors significantly increases the refractive index measurement range while maintaining excellent signal modulation (15 dBm for a refractive index of 1.477). Furthermore, our sensor features a wide measurement range (1350-1700 nm).
This study employs the Dynamic Laser Speckle Technique (DLST) with grey-level co-occurrence-matrix analysis to detect 5 %burra-sugar adulteration across eight commercial honeys. A spatially filtered He-Ne laser beam interacted with liquid samples, producing speckle images captured at 64 fps by a CMOS sensor. Seven statistical textural metrics were extracted from the speckle images using MATLAB software. Average absolute percentage change in metrics such as cluster prominence, variance, and contrast changes by 12.4%, 6.2%, and 5.5% respectively. The average change in inertia moment (IM) and absolute value difference (AVD) is -7.64% and -5.39 %, respectively. DLST costs <$1 per sample, offering an economical safeguard for honey quality.
This study explores the use of Fast Fourier Transform (FFT) for denoising signals from a Localized Surface Plasmon Resonance-based Optical Fiber (LSPR-OF) sensor. By applying FFT, high-frequency noise was effectively suppressed, enhancing measurement precision. An optimal cut-off frequency of 0.01 was identified for balancing noise reduction and signal preservation. Results demonstrated shifts in resonance wavelengths, with varying sensitivity across metals. The findings highlight the potential of FFT filtering to improve the clarity of LSPR spectrum.
its inception three decades ago, liquid crystal (LC) microwave phase-shifting technology has made tangible and highly scalable improvements. Although LC-enabled phase shifts (measured in degrees or radians) have arguably produced a wealth of discoveries, delay length and delay duration (measured in picoseconds) have perhaps garnered significantly less attention. In this work, we numerically characterize the delay times and lengths of various LC-enabled variable delay line designs at the 60 GHz band, identifying the optimal dielectric constant state (baseline) that achieves a 50-ohm match while minimizing spikes and turbulence in the frequency response. In practice, the increase in the conventional figure-of-merit metric (i.e., the ratio of the maximum phase shift to the maximum insertion loss) has coincided with the ripples ramped up in the frequency response of the time delay. By suitably designing the geometry's matching baseline at the LC's permittivity state of 3.1, we achieve a quasi-constant delay time (and length) with minimised amplitude variations (standard deviation of 0.72 fs) across 54 GHz to 66 GHz, i.e., highly desirable for minimum squint and mitigated sidelobe for 60 GHz beam steering applications.
and microplastics represent an increasing threat to both the environment and human health, particularly in enclosed spaces such as beauty salons. This study presents a preliminary characterization of microplastic particles generated during the milling of various nail styling materials. Morphological analyses were carried out using optical microscopy and scanning electron microscopy (SEM), while chemical composition was determined by FTIR spectroscopy. The results revealed that the microplastic particles ranged in size from a few to several tens of micrometers and exhibited diverse morphologies. Component identification confirmed the presence of potentially irritating, allergenic, and asthma-inducing substances such as acrylates. These findings highlight the need for further investigation into inhalation exposure among beauty salon workers, as well as the necessity of emission control strategies for microplastics in such environments.
Volatile Organic Compounds (VOC) detection system for lung cancer diagnosis through deep learning (DL) technology is implemented in a special Hollow-Core Photonic Crystal Fibre (HC-PCF) sensor platform. COMSOL Multiphysics is used to simulate the HC-PCF. A hexagonal lattice structure of silica material with 1 mu m pitch dimensions and 0.5 mu m air hole diameters allow for exceptional light guidance and VOC interaction when detecting exhaled breath components. The sensor achieves a remarkable refractive index sensitivity of 920 nm/RIU for detecting cancerous and non-cancerous VOC profiles. The refractive index measurements of lung cancer-related VOC samples fell within 1.380 to 1.392, while VOC samples from healthy patients ranged from 1.350 to 1.360. Sensor spectral response data processing relied on a Convolutional Neural Network (CNN) model that was trained to distinguish different VOC signature patterns. When applied to a datasetof 1,200 breath samples consisting of 600 cancer-positive and 600 healthy specimens, the CNN architecture reached a 96.3% overall classification accuracy combined with 94.7% sensitivity and 97.8% specificity.
Wide-angle capability is essential for holographic near-eye displays. Most of these employ phase-only spatial light modulators, so CGH must be encoded as phase-only holograms (PoHs). Thus, this paper investigates three known encoding methods: double phase hologram (DPH), direct phase only hologram (D-PoH), and complex amplitude modulation (CAM). To determine the most optimal phased-encoding method, we evaluate them by field of view, image quality, and diffraction efficiency. It was found that CAM gives very low brightness and quality; thus, improvement of the CAM is proposed. Also, we conclude that D-PoH is the optimal method for the wide-angle case.
of spectral output of a graphene light source integrated with electrostatically actuated membrane were performed, taking into account the light source geometry and the deflection range silicon membrane. Concept of miniaturized, tuneable light source operating in IR spectral range is presented. Maximum wavelength tuneability is discussed.
