A sensing configuration for fluid evaporation monitoring using a suspended-core fiber tip is proposed. Strong differences between the evaporation processes of acetone and isopropyl alcohol were observed, both in terms of the signal's intensity fluctuations and total duration. In each fluid, the main signal variations were due to changes in reflectivity inside a collapsed region of the suspended-core fiber near the spliced interface with a standard single-mode fiber. After further analysis with a wider array of substances, this configuration could, in the future, be used to detect and study the evaporation of different volatile organic compounds.
power divider incorporating k/4 transformers is properly designed to feed the array elements. The elements of the array are spaced at a distance of 0.8k 0 from each other in both x-and y-directions.ABSTRACT: A new microstructured optical fiber is presented as a sensor of acetone evaporation. Sensing is performed by observing the time response of the reflected signal at 1550 nm when the device is dipped in acetone or a 50% acetone-50% water mixture. The sensor consists on a caterpillar-like microstructured fiber spliced to a single-mode fiber, where the spliced end of the sensor has a transversal microfluidic channel etched using focused ion beam. Upon heating, different behaviors are visible between the dipping and the evaporation of acetone. The sensor is able to track the evaporation of acetone and to distinguish between pure acetone and a 50% acetone-50% water mixture. The sensor is also able to detect when the acetone in a mixture with water is fully evaporated. The detection of water vapor with no particular orientation of the sensor is achieved due to the presence of the microfluidic channels.ABSTRACT: This article presents a thorough investigation of the use of shorting posts to widen the bandwidth and coupling coefficient range of a patch quadrature coupler. The lumped equivalent circuit is used to analyze the characteristics of two proposed shorting posts loaded patch configurations. It is shown that by loading shorting post on the center of a patch, the bandwidth of coupler with loose coupling can be significantly improved. The patch configuration with four shoring posts is also proposed to provide a loose coupling coefficient up to 15 dB, which cannot be achieved using the conventional configuration. For demonstration purposes, two quadrature couplers were designed to exhibit 10 and 15 dB coupling coefficients with bandwidths of 29% and 19.2%, respectively. V C 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:683-688, 2016; View this article online at wileyonlinelibrary.com.
International audienceA segment of a suspended-core microstructured fibre was dipped in a droplet of acetone and the evaporation dynamics of remaining acetone inside the cavity were simultaneously analysed with an optical microscope and an optical spectrum analyser. When the fibre is immersed it suffers a 14 dB signal drop. Different menisci form in each cladding cavity, with different evaporation times and rates. The signal restores its initial state not when the evaporation process is complete but after the collapse of a dominant meniscus
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