This work presents an interrogator system based on an erbium-doped fiber ring cavity for refractive-index measurements. This fiber ring cavity is assisted by a fiber Bragg grating and a phase-shift fiber Bragg grating, both with a similar central emission wavelength to increase the output power levels.

We present a long-range Brillouin optical time domain reflectometer (BOTDR) based on photon

counting technology. We demonstrate experimentally the ability to perform a distributed temperature measurement, by detecting a hot spot in a thermal bath at 100 km, and the possibility to achieve measurement until 120 km with a spatial resolution of 10 m. We use the slope of a fiber Bragg grating (FBG) as a frequency discriminator, to convert count rate variation into a frequency shift. A performance study of our distributed sensor as a function of spatial resolution is also presented.

The aluminum nitride bandgap energy matches that of the salt-water binding energy. Here we study the effect of 405-nm light on the rates of evaporation when solutions are imbibed within a porous ceramic aluminum nitride wick. Sensitive measurements are taken in a self-referencing setup and compared to the light-induced capillary fluid response. Evaporation rates increase with light illumination when the solution is more saline, which indicates charge-transfer characteristics. Our results show consistent trends and potential for photonic environmental applications in salt-water separation processes.

The Terahertz region electromagnetic spectrum offers significant importance for space observations, including the ability to penetrate dust clouds and atmosphere of planets, as well as detect the unique spectral signatures of various molecules and atoms. Thus, terahertz spectrometers are of significant importance in space observations. However, current terahertz spectrometers face several challenges that limit their performance and application. The key problems include low resolution and sensitivity, limited bandwidth, large volume, and complexity. In this paper, we introduce the concept for a compact terahertz spectrometer that incorporates a metasurface. We start by modelling, designing, and fabricating the metasurface sample, aiming to optimize its performance within bandwidth from 1.7 to 2.5 THz. Next, we utilize a Quantum Cascade Laser that operates at 2.1 THz to validate our concept. Finally, we apply the spectrum inversion method to achieve a high resolution with R (f/Δf) 273. Our results showcase the successful demonstration of a compact and high-resolution terahertz spectrometer. Our findings provide a valuable strategy for spectrometer design, which can be widely applied optics field, particularly in space detection.