OPTICAL FIBER SENSOR

摘要

An optical fiber sensor for measuring the refractive index of a medium to be measured with high sensitivity. The optical fiber sensor has a simple structure and enables measurement of a refractive index in a wide range. The optical fiber sensor comprises an optical fiber (1) for causing a transmission loss due to leakage in the clad propagation mode from a portion of a core (4) and a clad (5) where a Bragg grating (9) is provided, a light source (2) for permitting light in a wavelength band in the clad propagation mode to enter the optical fiber (1), and a light-receiving section (3) for receiving the transmitted or reflected light transmitted through the core (4) and the clad (5) at the portion where the Bragg grating (9) is provided. The refractive index of the medium to be measured in contact with the clad (5) is measured according to the total intensity of the light received by the light-receiving section (3). The Bragg grating (9) is inclined at a predetermined angle of inclination to the vertical line vertical to the length direction of the optical fiber (1).