No abstract

In this paper a new rotary position sensing structure based on a pair of fiber Bragg gratings (FBGs) is experimentally demonstrated with capability of detecting rotating angle of a rotor which is rotated in arbitrary direction or rotated in the same direction infinitely. Moreover, owing to its miniature size, this structure can also be used for small rotary apparatus as a tiny rotating position sensor. The operation mechanism is mainly based on the difference between the wavelength shifts of two FBGs respectively due to the axial strain caused by bending the cantilever towards the angular direction corresponding to the rotating position of rotary shaft. A deviation of 1.1 degrees for rotary angle detecting is obtained.

In this work, we propose a novel fiber sensor that is based on an air-gap long-period fiber grating (AG-LPG), which is fabricated by combining fiber side polishing with fiber lithography. Its sensing mechanism is based on the loss-peak wavelength shift of the AG-LPG as the refractive index around the sensing head varies. Experimental results show that the maximum sensitivity is 620 nm/unit index (1.1 nm/%) in the sensing of various sugar solution concentrations. This novel sensing head provides a simple, reliable, repeatable, accurate, and nondestructive approach for detecting various chemical solutions and mixing gases and for biomedical applications.

No abstract

A simple refractive index sensor based on a small section of fiber damaged by the fiber fuse is proposed and demonstrated with a sensitivity of 350.58 nm/refractive index unit (RIU). For comparison, a hetero-core structure fiber sensor composed of a short no-core fiber (NCF) sandwiched between two pieces of single-mode fibers is demonstrated with a sensitivity of 157.29 nm/RIU. The fiber fuse technique can allow mass production of sensors by incorporating small sections of the damaged fiber of any type into each device. We believe this is the first application of the periodic damage tracks in optical fibers formed by the fiber fuse.