Guei-Ru Lin

Optical Fiber Sensor Based on Air-Gap Long-Period Fiber Gratings

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.

Random Rotary Position Sensor Based on Fiber Bragg Gratings

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.

Dual-parameter sensor based on a no-core fiber and fiber Bragg grating

A dual-parameter optical sensor is demonstrated by connecting together a fiber Bragg grating and a no-core fiber. The hybrid configuration permits the detection of the temperature and the external refractive index.

Harnessing the fiber fuse for sensing applications

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.

A refractive-index fiber sensor by using no-core fibers

A simple, small-size, compact and high-sensitivity refractive-index sensor composed of a short no-core fiber (NCF) about 20 mm in length sandwiched between two pieces of single-mode fibers is proposed in this paper. The index measurement is experimentally demonstrated with the sensitivity of 7792.85 nm/ RIU in the range from 1.440 to 1.454 and 227.14 nm/ RIU in the range from 1.300 to 1.430. This sensing mechanism is based on the induced multi-mode interfering wavelength shift in the no-core fiber when the reflective index of the fiber outside is changed.

A rotational angle sensor based on fiber bragg gratings

A new rotational angle sensor composed of two FBGs glued axially on a metal-rod surface driven bent by attraction of a magnetic disk is proposed. Whenever an external force is applied in the end of this sensor, these two FBGs undergo a strain caused by a shaft rotation to result in their central wavelength shifts respectively. This sensor can precisely to detect the random rotation angle in both static and dynamic conditions. The nice sensing performance including linear response, fine resolution, negligible hysteresis, and long-term stability are experimentally demonstrated.

A random-rotational angle fiber sensor

This paper has successfully achieved a new type optomechanical rotational angle sensor which consists of two FBGs glued axially on a capillary surface that is driven bent by attraction of a magnetic disk. Whenever an input force exerts on the end of this sensor, these two FBGs undergo strain caused by shaft rotation and result in their central wavelength shifts respectively. This sensor can be used to accurately detect random rotation angle in both static and dynamic conditions except the maximum deviation of 0.876 deg from 195 deg. The excellent sensor characteristics including linear response, fine resolution, negligible hysteresis, and long-term stability are experimentally demonstrated.

Random-rotational angle sensor based on fiber Bragg gratings

A novel rotational-position sensor consists of two FBGs glued axially on a capillary surface and driven bent by attraction of a magnetic disk, which accurately detects random rotation angle in both static and dynamic conditions.

A novel refractive index sensor based on an induced micro-structure fiber

We demonstrate the first application of the periodic damage tracks in optical fibers formed by the fiber fuse. A refractive index sensor with a sensitivity of 350 nm/refractive index unit (RIU) is experimentally demonstrated. This technique can allow mass production by incorporating small sections of the damaged fiber into each device. It can also be applied widely in different types of sensing systems by coating sensing material on the damaged fiber’s cladding surface.

A three-dimension tilt-meter based on fiber gratings

A tilt-meter consists of two long-period gratings mounted axially on the inner wall of a cylindrical container and has a nice linearity in the tilt range from 0 to +20 degree in a random direction.