A fiber-optic sensor is a sensor that converts measured light into light characteristics (intensity, phase, polarization state, frequency, wavelength) by utilizing the light-transmitting characteristics of the optical fiber.

With the continuous development of social industrialization and the continuous advancement of the sensor industry, optical fiber sensors have gradually been used in industrial production. Below we analyze the specific classification, advantages and disadvantages of fiber optic sensors.

Fiber optic sensors can be divided into two categories: active (sensing) sensors and inactive (transmitting) sensors. Below we introduce the advantages and disadvantages of the two fiber sensors.

1, the action sensor

The action type sensor uses the characteristics of the fiber itself to use the fiber as a sensitive component, and is measured to modulate the light transmitted in the fiber to change the characteristics of the intensity, phase, frequency or polarization state of the transmitted light, and then modulated by the pair. The signal is demodulated to derive the signal under test. The optical fiber is not only a light guiding medium but also a sensitive component, and the light is modulated and modulated in the optical fiber, and a multimode optical fiber is often used.

Advantages: compact structure and high sensitivity

Disadvantages: special fiber must be used, high cost

Typical examples: fiber optic gyroscopes, fiber optic hydrophones, etc.

2, non-active sensor

Inactive sensors use other sensitive components to sense the measured changes. Optical fibers are only used as the transmission medium for information, and single-mode fibers are often used. The optical fiber only acts as a light guide, and the illumination is modulated on the fiber-type sensitive component.

Advantages: no special fiber and other special technologies, easy to implement, low cost.

Disadvantages: low sensitivity.

Most of the practical applications are non-functional fiber optic sensors.

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