An optical fiber is used not only as a transmission medium but also as a sensor in fiber-optic sensing technology. Novel specialty fibers and relevant technologies have been developed for various application fields, such as avionics, infrastructures, atomic plants and oil&gas industries. In this paper, recent progress in the fiber-optic sensing is reviewed with a focus on the specialty fibers and fiber-optic components.

抄録全体を表示

This paper describes the development and applications of a fiber-optic electric current sensing technique with stable properties and sensing devices with a compact, simple, and flexible structure. We achieved special sensor characteristics with a low birefringence fiber as the Faraday-effect sensing element and also created sensing schemes that matched the fiber's features. By exploiting the sensing technique’s excellent features, we developed various current monitoring devices and systems and applied them at an electric power facility.

抄録全体を表示

This paper reviews fiber optic sensor applications in the field of space engineering. Some of the R&D activities introduced are; (1) structural health monitoring of cryogenic liquid hydrogen tanks, (2) FBGbased hydrogen sensors, (3) thermal strain monitoring of sensing coils in fib

抄録全体を表示

Fiber-optic sensing technique using a thin-film bandpass filter was demonstrated. A bandpass filter on fiber-end (BOF) sensor has broad spectrum curve which can detected by simple reflectometer. It has a possibility to construct inexpensive multi-sensing systems. BOF sensor can detect ordinary temperature with accuracy of ± 0.5˚C, and it has possibility to use for fiber-optic pressure sensing and hydrophone.

抄録全体を表示

Tilted Fiber Bragg Grating (TFBG) is expected to be used for such sensors as refractometers, twist sensors, liquid level sensors, chemical sensors and biosensors. We review its fabrication techniques and its refractive index measurements and developed a simplified technique to fabricate TFBG for simultaneous measurements of the refractive index and the temperatures of liquids. We used a combination of a 4ω Nd:YAG laser and a phase mask, which is simpler than a conventional method using a 2ω cw Ar+ laser and a Lloyd mirror interferometer. We calculated TFBG’s cladding modes by the multi-layer method and estimated the temperature coefficient of the water’s refractive index to be about ‒1×10‒4 /K using our fabricated TFBG sensor.

抄録全体を表示