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In this paper, it is proposed and experimentally investigated a sensor structure based on a core diameter mismatch technique for strain sensing. An uncoated short section of multimode fiber is spliced between two standard single mode fibers forming the sensor structure, called the SMS (single‐mode‐multimode‐single‐mode) sensor. The proposed SMS sensor, in the strain analysis, generates destructive or constructive interference patterns as load or strain are applied, changing the power of the optical signal only, without varying the wavelength. The sensor configuration offers several motivating attributes, such as easy fabrication, low‐cost, high‐efficiency and high sensitivity, moreover allows interrogation of the optical signal using the transmitted or reflected total optical power. The results and these advantages indicate that the proposed SMS sensor device is suitable for strain measurement, which is helpful in a broad range of applications, for instance, structural health monitoring. [ABSTRACT FROM AUTHOR]

ABSTRACT In this work, it is proposed a technique to implement an intensity sensor based on the generation of a double-reflecting (ghost) signal in optical time domain reflectometry (OTDR). The intensity sensor is supported by a singlemode-multimode-singlemode (SMS) fiber structure combined with a fiber loop mirror (FLM). The results of the displacement sensitivity show linear behavior for both the first-reflecting and double-reflecting signals with linear slopes of approximately −4.5 dB/mm and −6 dB/mm, respectively. The displacement resolution achieved is ∼0.28 mm. It is also found that the system is able to read periodic displacement variations in the millisecond time scale applied to the sensing head. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1312-1315, 2015 [ABSTRACT FROM AUTHOR]

ABSTRACT In this article, it is proposed an interrogation and multiplexing system based on optical time domain reflectometer for fiber loop mirror coupled intensity sensors. Pulse width of approximately 100 ns enabled to attain a dynamic range of approximately 18 dB. Good linearity was achieved with a −13.3 dB/mm slope. The resolution of the sensing head was 0.027 mm. The proposed interrogation system showed to be an alternative technique for multiplexing and remote sensing. © 2014 Wiley Periodicals, Inc. Microwave Opt Technol Lett 56:2860-2864, 2014 [ABSTRACT FROM AUTHOR]