a b s t r a c tSome smart windows make use of suspended particle devices (SPDs) which are made of charged rodshape particles that change their orientation in an applied electric field, thereby allowing transmittance control. In this work, the electro-optical behaviour of a commercial SPD is analyzed. Impedance analysis shows characteristics similar to those of a Randles circuit, and a modified equivalent circuit is proposed and experimentally validated. Intermediate levels of transmittance are obtained using a customized field programmable gate array (FPGA)-based electrical circuit. Finally, measurements are taken to check the applicability of the SPD device and control system in smart glazing or photonic applications.
Potential niches for Power-over-Fiber (PoF) technique can be found in hazardous areas that require controlling unauthorized access to risk areas and integration of multiple sensors, in scenarios avoiding electromagnetic interference, and the presence of ignition factors. This paper develops a PoF system that provides galvanic isolation between two ends of a fiber for remotely powering a proximity sensor as a proof of concept of the proposed technology. We analyze scalability issues for remotely powering multiple sensors in a specific application for hazardous environment. The maximum number of remote sensors that can be optically powered and the limiting factors are also studied; considering different types of multimode optical fibers, span lengths and wavelengths. We finally address the fiber mode field diameter effect as a factor that limits the maximum power to be injected into the fiber. This analysis shows the advantages of using Step-index versus Graded-index fibers.
A fast fiber-optic two-color pyrometer operating on the optical communication bands is designed for temperature measurements in machining processes. Off-the-shelf low-loss fiber-optic demultiplexers and optoelectronics equipment are used in order to obtain a cost-effective sensing solution while reducing both the temperature measurement error and the minimum measurable temperature. The system is capable of measuring highly localized temperatures without using collimation lens. The designed pyrom-eter allows measuring temperature in the range from 300 to 650 °C, achieving a full-scale temperature error as low as 4%. Factors in-fluencing the temperature measurements are studied in order to identify the sensor limitations, such as a possible damage on the end of the optical fiber, the spectral loss attenuation and responsivity, or the distance between the fiber end and the target. Finally, this pyrometer is applied in a turning process, using a fiber-optic sensor embedded on a standard tool holder. Temperature measurements on the Inconel 718 are reported showing a good agreement with the simulations.
We propose the integration of power over fiber in the next generation 5G radio access network front-haul solutions based on spatial division multiplexing with multicore fibers. The different architectures in both shared-and dedicated-core scenarios for power over fiber delivery and data signals are described. The maximum power to be delivered depending on the efficiencies of the different components is addressed as well as the limits of the delivered energy to avoid fiber fuse and non-linear effects. It is shown how those limits depend on high power laser linewidth, fiber attenuation, link length and fiber core effective area. The impairments related to non-linear effects, multicore fiber crosstalk and temperature are also theoretically analyzed. Experiments show there is no degradation of signal quality for feeding powers of several hundreds of milliwatts for both scenarios in 4-core multicore fibers. This study helps in designing future power by light delivery solutions in Radio over Fiber systems with multicore fibers.
Abstract:The design and development of a plastic optical fiber macrobend temperature sensor is presented. The sensor can op-erate in a temperature range from −55 to 70 °C and has a linear response versus temperature with a sensitivity of 8.95·10−4 °C−1. The sensor system uses the ratio of transmittance at two wave-lengths to implement a selfreferencing technique in order to avoid undesirable power fluctuations influence. The transmittance ratio precision is 0.1%. An analysis has been developed to find the two wavelengths which ratio offers the highest linearity and sensitiv-ity response. Experimental results are successfully compared with theoretical approaches.
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