Substrate-Integrated Waveguide Microwave Sensor for Water-in-Diesel Fuel Applications

A water-in-diesel microwave sensor based on a substrate integrated waveguide (SIW) microwave applicator is designed and characterized in this study. The interaction between the microwave electromagnetic field and the diesel fuel contaminated with small concentrations of water is obtained via suitable radiating slots placed on the top of an SIW waveguiding structure. The SIW applicator working frequency is chosen by observing the behavior of the complex dielectric permittivity of the fuel–water blend based on a preliminary wide band investigation. The performances of the SIW microwave sensor are evaluated in terms of scattering parameter modulus |S21| as a function of the water concentration in ppm. The best sensitivity Δ|S21|Δρ=1.42 mdB/ppm is obtained at a frequency of f=9.76 GHz, with a coefficient of determination R2=0.94. The sensor is low-cost, low profile and ensures a good sensitivity for constant and real-time monitoring.

Theoretical Investigation of Oxazine 170 Perchlorate Doped Polymeric Optical Fiber Amplifier

Optical signal amplification in the waveguiding structure of optical fibers can be used for optical telecommunication systems and new light sources constructions. Organic dyes doped materials are interesting for new applications in polymeric optical fibers technology due to their benefits (efficient fluorescence, high absorption cross section, and easy processing). This article presents a numerical simulation of gain in poly(methyl methacrylate) optical fiber doped by Oxazine 170 Perchlorate. The calculated gain characteristic for the used dye molar concentration (0.2·10-6–1.4·10-6) and pump power (1–10 kW) is presented. The fabricated fluorescent polymeric optical fiber is also shown. The presented analysis can be used for optical amplifier construction based on dye-doped polymeric optical fiber (POF).

A Microring Temperature Sensor Based on the Surface Plasmon Wave

A structure of microring sensor suitable for temperature measurement based on the surface plasmon wave is put forward in this paper. The sensor uses surface plasmon multilayer waveguiding structure in the vertical direction and U-shaped microring structure in the horizontal direction and utilizes SOI as the thermal material. The transfer function derivation of the structure of surface plasmon microring sensor is according to the transfer matrix method. While the change of refractive index of Si is caused by the change of ambient temperature, the effective refractive index of the multilayer waveguiding structure is changed, resulting in the drifting of the sensor output spectrum. This paper focuses on the transmission characteristics of multilayer waveguide structure and the impact on the output spectrum caused by refractive index changes in temperature parts. According to the calculation and simulation, the transmission performance of the structure is stable and the sensitivity is good. The resonance wavelength shift can reach 0.007 μm when the temperature is increased by 100 k and FSR can reach about 60 nm. This structure achieves a high sensitivity in the temperature sense taking into account a wide range of filter frequency selections, providing a theoretical basis for the preparation of microoptics.