In this letter, a curvature sensing setup based on a fiber ring laser containing a long-period fiber grating (LPFG) is presented. The LPFG operates as a wavelength selective filter and as a curvature sensing head. The LPFG consists of a periodically tapered fiber section written by a CO2-laser glass processing system. Experimental results show that by increasing the curvature values from 0 to 0.266 m-1, the laser wavelength emission shifts linearly from 1572 to 1560 nm, and a curvature sensitivity of -42.488 nm/m-1 is achieved. Additionally, the laser emission has a linewidth of 0.05 nm, a slope laser efficiency of 0.43single-mode suppression ratio (SMSR) of 60 dB. Finally, this fiber laser offers output power stability at room temperature, compactness, and robustness.

In this paper, a gas sensing system based on a conventional absorption technique using a single-mode-fiber supercontinuum source (SMF-SC) is presented. The SC source was implemented by channeling pulses from a microchip laser into a one kilometer long single-mode fiber (SMF), obtaining a flat high-spectrum with a bandwidth of up to 350 nm in the region from 1350 to 1700 nm, and high stability in power and wavelength. The supercontinuum radiation was used for simultaneously sensing water vapor and acetylene gas in the regions from 1350 to 1420 nm and 1510 to 1540 nm, respectively. The experimental results show that the absorption peaks of acetylene have a maximum depth of approximately 30 dB and contain about 60 strong lines in the R and P branches, demonstrating a high sensitivity of the sensing setup to acetylene. Finally, to verify the experimental results, the experimental spectra are compared to simulations obtained from the Hitran database. This shows that the implemented system can be used to develop sensors for applications in broadband absorption spectroscopy and as a low-cost absorption spectrophotometer of multiple gases.

This paper presents a displacement sensor designed to achieve the Optical Vernier Effect (OVE) through a simple yet robust configuration, enhancing sensitivity and precision in small displacement measurements. The sensor structure comprises a few-mode fiber (FMF) placed between two single-mode fibers (SMF) in an SMF-FMF-SMF (SFS) configuration. A series of distinct configurations of concatenated Mach–Zehnder fiber interferometers (MZFI) were examined, with the lengths of the reference FMF (FMF_Ref) and sensing FMF (FMF_Sen) adjusted to track the spectral envelope shifts. The results demonstrate that the direction of the spectral shift is governed by the ratio between the FMF_Ref and FMF_Sen lengths. The sensor achieved a sensitivity of up to 39.07 nm/mm and a magnification factor (M factor) of up to 50.09, demonstrating exceptional precision and adaptability across a range of applications. The proposed configuration also enhances the overall sensor performance, highlighting its potential for broader use in fields requiring precise displacement monitoring.

In this study, a switchable ytterbium-doped fiber laser based on symmetrical long-period fiber grating (LPFG) is presented. The LPFG is used as a wavelength-selective filter (WSF). Utilizing this WSF, the laser can emit one, two, or multiple stable output beams by adjusting the temperature on the LPFG from 20 C to 600 C. In addition, switching is also possible by adjusting the curvature of the LPFG from 0.399 to 0.709 m-1. The symmetrical LPFG was fabricated by combining the cladding shaping with the thermal core expansion techniques by using a CO2-laser LZM-100 glass-processing system. The experimental results show a side-mode suppression ratio (SMSR) of 49 dB and a linewidth of 0.06 nm, within the range from 1038 to 1080 nm. In conclusion, the main achievement of this switchable laser is the high SMSR and stable output for high values of temperature, using a repeatable, simple, easy construction, and cost-effective laser tuning technique.

An experimental demonstration for generating harmonics in the optical Vernier effect (OVE) by cascading tapered single-mode fibres (SMF28) is presented. The tapered optical fibres conformed to a pair of in-series Mach-Zehnder fibre interferometers (MZFI), in which one MZFI was a reference while the other was a sensor. The first-order harmonic was achieved by increasing the distance between tapers of the sensor MZFI by a multiple of (i + 1) times the distance between tapers of the reference MZFI plus a mismatch factor. A series of experiments using an individual MZFI and two MZFIs with traditional and harmonic OVE as displacement sensors were performed to compare their sensitivities and magnification factors and demonstrate the improving the sensitivity. The displacement sensor with the first-order harmonic exhibited a maximum sensitivity of −33.3 nm/mm with an M-factor of 8.53 in the mm range.

El proyecto tiene como objetivo apoyar la actividad agrícola en beneficio de familias maya hablantes que habitan en comunidades rurales, ayudando en la producción de alimentos para su propio consumo y comercialización, generando un apoyo a su economía familiar y autoempleo. La investigación responde a la necesidad de optimizar el uso del agua y mejorar la eficiencia del riego en entornos rurales, donde los recursos hídricos son escasos, llegando incluso a recibir el servicio de agua potable por las mañanas o tardes durante un tiempo muy corto, por lo que los pobladores recolectan el agua en diversos contenedores para su posterior uso, priorizando según sus necesidades donde utilizarlo. Se empleó una metodología cualitativa que facilitó la observación del impacto del prototipo basado en un microcontrolador ESP32 para el llenado de los tanques. Como resultado, se desarrollaron prototipos que ayudaron en el suministro y control de los niveles de agua en los tanques de ferrocemento, permitiendo una mejor optimización y uso del agua. En conclusión, el trabajo resalta cómo la integración de tecnologías IoT en la agricultura contribuye a prácticas de riego más sostenibles y eficientes, promoviendo un uso responsable de los recursos hídricos y mejorando la productividad de los cultivos en espacios reducidos.