Types and Sensing Methods of Fiber Optic Sensors

With continuous technological progress, fiber optic sensors play an increasingly important role across many fields. Fiber optic sensors use light properties to detect and measure physical quantities such as temperature, pressure, and displacement. Depending on the application scenario, different sensing methods can be employed to meet specific requirements.

First, based on operating principles, fiber optic sensors can be divided into two main categories: interferometric fiber optic sensors and scattering-based fiber optic sensors.

Interferometric fiber optic sensors use optical interference to measure physical quantities. A common example is the fiber interferometer, which splits light into two paths—one serving as the reference and the other as the sensing path. Changes in the measured quantity cause optical path differences, altering the interference pattern; analyzing these changes yields the measured value.

Scattering-based fiber optic sensors rely on light scattering phenomena within the fiber. These sensors include Raman scattering, Brillouin scattering, and fiber Bragg grating (FBG) sensors.

Raman scattering sensors exploit Raman scattering to measure physical quantities. As light travels through the fiber and interacts with molecules, Raman-scattered light is generated; its characteristics convey information about the measured quantity.

Brillouin scattering sensors use Brillouin scattering originating from interactions between light and acoustic phonons in the fiber. Measuring Brillouin-scattered light provides information about the sensed parameter.

Fiber Bragg grating sensors use periodic refractive index variations in the fiber. When light passes through an FBG, Bragg reflection occurs; measuring reflected spectral characteristics yields the measured information.

Besides sensing mechanisms, fiber optic sensors can also be categorized by application, such as fiber optic temperature sensors, pressure sensors, and displacement sensors.

In summary, fiber optic sensors come in various types and sensing modes; choose the appropriate sensor based on specific needs. As technology advances, fiber optic sensors will continue to expand their applications and bring more convenience and innovation.