The basic working principle of fiber optic sensors is to feed the light from the light source into the modulator through the fiber optic, causing the measured parameters to interact with the light entering the modulation region, resulting in changes in the optical properties of the light (such as intensity, wavelength, frequency, phase, polarization state, etc.), which is called the modulated signal light. Then, by utilizing the influence of the measured light on the transmission characteristics, the measurement is completed.
There are two measurement principles for fiber optic sensors. Physical type fiber optic sensors utilize the sensitivity of optical fibers to environmental changes, transforming input physical quantities into modulated optical signals. Its working principle is based on the optical modulation effect of optical fibers, which refers to the phenomenon that the transmission characteristics of optical fibers, such as phase and light intensity, will change when external environmental factors such as temperature, pressure, electric field, magnetic field, etc. change. A structured fiber optic sensor is a measurement system composed of light detection elements (sensitive elements), fiber optic transmission circuits, and measurement circuits. The fiber optic only serves as the propagation medium of light, so it is also known as a transmission type or non functional fiber optic sensor.
