Optical fiber sensor for variable pressure measurement with temperature compensation

The state of polarization (SOP) of light in optical fiber is very sensitive to any perturbation which is not symmetric about the fiber axis. The polarization intensities of light in the fast and slow axes of the fiber are affected by the applied pressure in the form of refractive index variations in these two axes known as "birefringence effect". The potential advantage of optical fiber sensors using polarization variation technique is that the perpendicular optical signals can be transmitted to and from the sensing region without recourse to electrical connection. The measurement of these bi-directional intensities is calibrated in terms of pressure at the sensing portion of the fiber. In this paper, a new method using a 3-dB coupler for splitting light beam to provide a reference signal has been proposed.