Current Issue : October-December Volume : 2026 Issue Number : 4 Articles : 5 Articles
Low-cost optical sensors have emerged as promising tools for in situ freshwater quality monitoring, offering the potential to expand spatial and temporal data coverage, particularly in community-based monitoring projects. However, despite rapid technological development of low-cost optical sensors, analytical validation practices of these devices remain poorly studied. This study aims to systematically and critically assess analytical validation practices applied to low-cost optical sensors based on absorbance, fluorescence, colorimetry, and light scattering, potentially designed for community-based freshwater monitoring. A total of 40 studies were analysed to evaluate how key analytical performance parameters, including sensitivity, accuracy, precision, and repeatability, as well as comparison with reference methods or benchtop instruments, were assessed and reported in relation to established validation guidelines. The analysis revealed substantial heterogeneity and critical gaps in validation approaches. While most studies report sensitivity metrics such as limits of detection and quantification, comprehensive evaluation of key analytical parameters such as accuracy, precision, and reproducibility was often limited. The reliance on single calibration experiments and high determination coefficients (R2) frequently overestimates sensor performance. The lack of open-source materials further limits reproducibility and deployment: essential information such as design files, calibration procedures, and open-source resources is often incomplete or unavailable. To address these limitations, we propose a structured framework for validation and reporting that integrates established analytical guidelines with the practicalities of low-cost sensor development. Adoption of this approach would enable more consistent performance evaluation, improving reproducibility and facilitating comparison across studies and devices. Overall, strengthening analytical validation and reporting practices is essential to support the transition of low-cost optical sensors from proof-of-concept systems to reliable analytical devices for freshwater quality monitoring....
The article discusses promising methods of data transmission using laser radiation. A comparative analysis of optical (non-laser) and laser communication was conducted, and experimental modeling of two channels was performed, including a mock-up. The optical communication channel model is based on an amplitude-modulated infrared (IR) LED and a narrowly focused laser transmitter. The model of the laser communication channel included a semiconductor laser source and a phototransistor receiver. As part of the work, the main characteristics of these communication channels were evaluated, including the maximum data transfer rate, maximum communication range, and quantitative measures of noise immunity for both channels. Significant differences were revealed, in particular, packet errors of 3–5 bits in a row were observed in the IR channel, which is explained by the inertia of the analog circuits of the receiving part. The laser system, on the contrary, demonstrated a uniform distribution of single errors due to the discrete nature of interference from background illumination. The article shows that both methods of organizing communication can be effectively used for information exchange tasks with a short distance between objects, particularly in groups of unmanned aerial vehicles....
Optical limiting is an intrinsic yet often overlooked nonlinearity in nanomaterial-based composites, traditionally regarded as detrimental in laser cavities and thus deliberately suppressed. Here, we demonstrate that optical limiting can instead be harnessed as a functional degree of freedom for intracavity control in ultrafast fiber lasers. Using a carbon nanotube/polydimethylsiloxane (CNT/PDMS) composite as a representative platform, we show the coexistence of optical limiting and saturable absorption, where the two nonlinearities play distinct and complementary roles. The CNT/PDMS composite exhibits a modulation depth of ∼ 3% with a low saturation intensity of ∼ 2.9 MW/cm2 for stable mode locking, together with a reversible optical limiting induced by photothermal loss under laser radiation. Time-resolved pump-probe measurement reveals a thermal recovery time of ∼ 33 μs, which is on a different temporal scale against ultrafast saturable absorption dynamics. When incorporated into the polarization-maintaining Er-doped fiber laser, saturable absorption governs pulse formation, while optical limiting provides intensity-dependent intracavity loss that reshapes the gain spectrum, enabling pump-controlled reconfigurable spectral engineering with non-mechanical and nondestructive nature. This work redefines intracavity optical limiting as a functional degree of freedom for reconfigurable ultrafast lasers and is extendable to various gain media and waveguide platforms....
When a light beam pulls an object toward the source, known as a tractor beam, it has become a subject of great interest due to its potential applications in nanotechnology, quantum technology, and biology. Studies of optical pulling force on gold particles with a size comparable to or larger than the operating wavelength are extremely rare. This paper proposes an approach to generate optical pulling force on gold Mie objects with a length of 2000 nm, much larger than the operating wavelength, ranging approximately from 720 to 830 nm. The proposed structure can facilitate pulling force on two different shapes—cylindrical and ellipsoidal, and these forces have been studied under various conditions. The emergence of such pulling force has been explained by physical parameters such as the Poynting vector, surface current density, and electric and magnetic field profile, as these collectively determine the pushing or pulling behavior of the gold particle by governing how the gold–germanium–aluminum environment shapes local field confinement, resonance phases, and electromagnetic momentum flow to control whether the particle scatters energy forward or backward. The proposed approach may offer a new way to perform optical manipulation of plasmonic objects without using costly materials....
Access to rigorous optical microscopy education remains unevenly distributed across the globe despite widespread use of optical methods. While lowerresourced settings certainly feel this burden, it is far from a foregone conclusion that such opportunities are ubiquitous, even at well-funded institutions. Despite a growing number of online educational resources and other tools, many biomedical researchers learn microscopy in a task-specific manner, and without the conceptual foundation to maximise the potential of its capabilities, robustly interpret data, avoid bias, and/or troubleshoot effectively. Given microscopy’s significant impact in the discovery process and status as a cornerstone scientific tool, we developed a remotely accessible, global, and highly interactive program to help address the education gap with respect to the fundamentals of microscopy, irrespective of one’s location or ability to access high-end platforms. Here we reflect on the design and evolution of the resulting ‘Widening the Lens’ (WtL) program: whatworked, what didn’t, and how the course adapted in response, with the intent of enabling others to leverage our experience to develop programs of their own. We also describe our partnership with critical network organisations, including the African BioImaging Consortium (ABIC) to implement aWtL based train-the-trainer model across the African continent. WtL demonstrates that equitable microscopy education is not only achievable, but that closing education gaps involves building a community in concert with likeminded educational opportunities and networks across the globe....
Loading....