Intensity Modulation based U shaped Plastic Optical Fiber Refractive Index Sensor

Abstract

An intensity modulation-based fiber optics refractive index (RI) measurement sensor is designed by using macro-bending the probe. After removal of cladding and macro bending, sensor becomes more sensitive for change in RI of analyte. The principle is based on evanescent field, intensity modulation and macro bending loss concept. This has been done by removing cladding portion in sensing region and then macro bending clad removed portion in U shape using thermal heating. The RI measurement with fiber optic sensor (FOS) is done by doing the geometric changes in sensor probe such as changing sensing region length in clad removed area, macro bending sensing region and by using multiwavelength LEDs as a light source. The wavelengths of LED falls in the visible spectrum. The sensitivity of sensor found to be good in the RI range of 1.33 to 1.41. The proposed RI sensor is compact, simple in design and less expensive and can be used in food and medical industry.