EDF ring laser using cascaded-chirped long period fiber grating for temperature measurement.

A novel tunable erbium-doped fiber ring laser (EDFRL) using a cascaded-chirped long period fiber grating (C-CLPG) as a wavelength selection element is proposed. The oscillation wavelength is determined by the one of the spectral peaks of the C-CLPG used, and the oscillation output provides a high signal to noise (S/N) ratio detection and a highly sensitive measurement of the temperature due to its high power and narrow spectral output. In the experiment, it is confirmed that the wavelength of the output shifts in accordance with the temperature-induced spectral shift of the C-CLPG transmittance spectrum and the temperature sensitivity is obtained to be ∼-0.2 nm/°C within the wavelength range of 1567.30 ∼ 1575.78 nm. The oscillation wavelength range is to be limited depending on the fringe spacing of the channeled spectrum of C-CLPG, which limits the temperature measurement range, but a data processing approach to solve this problem is additionally proposed and its availability is also presented.

Simultaneous multi-point measurement of strain and temperature utilizing Fabry-Perot interferometric sensors composed of low reflective fiber Bragg gratings in a polarization-maintaining fiber.

A fiber Bragg grating (FBG)-based multi-point sensing system for the simultaneous measurement of strain and temperature is proposed, with a Fabry-Perot interferometer (FPI) consisting of low reflective FBGs inscribed inside a polarization-maintaining (PM) fiber is introduced as a sensor head. A multi-point sensing method with high dynamic range and short measurement time can be realized by analyzing the reflection spectrum of low reflective FBG-FPIs, and a simultaneous measurement of strain and temperature using two orthogonal polarization modes is enabled by the high birefringence of a PM fiber. An experimental demonstration of multi-point measurement utilizing the proposed system is reported.

Evaluation of Human- and Animal-Specific Viral Markers and Application of CrAssphage, Pepper Mild Mottle Virus, and Tobacco Mosaic Virus as Potential Fecal Pollution Markers to River Water in Japan.

Five human-specific markers were detected in 59-74% of 27 human fecal-source samples collected in Yamanashi Prefecture, Japan. Similarly, potential human-specific markers, crAssphage, pepper mild mottle virus (PMMoV), and tobacco mosaic virus were detected in 96-100% of samples, with crAssphage showing the maximum concentration of 12.03 log copies/L. However, these markers were detected in 100% (3/3) of pig fecal-source samples, suggesting their applicability as general fecal pollution markers. Microbial source tracking analysis demonstrated that the rivers are contaminated by human and pig fecal sources. CrAssphage showed higher marker concentrations in river water samples than PMMoV, suggesting the preference of crAssphage to PMMoV as a marker of fecal pollution.