Feng Dejun

Refractive index sensor based on plastic optical fiber with tapered structure

This work reports a refractive index sensor made of plastic optical fiber (POF) with tapered structure. Transmission loss is measured when the external environments refractive index changes from 1.33 to 1.41. Three wavelengths (532, 633, and 780 nm) are used to evaluate the sensitivity of the sensor, and results indicate that 633 nm is the best sensing wavelength due to the increased levels of sensitivity achieved at this wavelength. A biconical sensing structure is designed to enhance the sensitivity of the sensor. A sensitivity of 950 μW/RIU at 633 nm is obtained for a biconical sensing structure when launched power is 1 mW. Due to its sensitivity to the refractive index and simple construction, POF with tapered structure has potential applications in the biosensing field.

D-Shaped Plastic Optical Fiber Sensor for Testing Refractive Index

In this paper, a D-shaped plastic optical fiber is fabricated by means of side-polishing technique for refractive index (RI) sensing. The principle of operation is based on the exploitation of the evanescent wave interaction of the propagating light with the external environment, resulting in optical transmission attenuation. Transmission loss is measured when the RI of the external medium changes from 1.333 to 1.455, exhibiting a good linear relationship between them. By changing the depth of the D-shaped groove and the curvature radius of the optical-fiber probe, the sensor sensitivity is optimized. This D-shaped fiber sensor is relatively simple of construction and low cost, which makes it attractive for RI sensing in biochemical region.