Radiation absorption creates electronic excited states that are trapped by localized defects for extended periods of time. Heating the material enables the trapped states to interact with phonons and decay into lower-energy. A fiber optic sensor measures a physical quantity by modulating the intensity, spectrum, phase, or polarization of light traveling through the optical fiber system. It's a device that converts light rays into electronic signals. The principles of FFPI sensors are mainly explained according to Equation 1. When perturbation is introduced to the sensor, the phase difference is influenced with the. Traditional fiber sensors based on different microstructures solely rely on the thermal expansion effect of silica material itself, limiting their usage primarily to temperature or pressure sensing. By employing thin film technology to form Fabry–Perot (FP) cavities on the end-face or inside the. A sensor that uses optical fiber as a detecting element is known as a fiber optic sensor.
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