Light source type of fiber optic sensor

Fiber optic sensors typically use LEDs, laser diodes, or superluminescent sources as their light source.

Fiber optic sensors rely on a light source to transmit optical signals through the fiber to detect changes in intensity, phase, wavelength, or polarization caused by the measurand. The most commonly used light sources are LEDs, which emit unpolarized light and are cost-effective, flexible, and suitable for general-purpose sensing applications . LEDs can also be combined with polarizing filters to produce linearly polarized light for specialized detection methods . For higher precision or long-distance sensing, laser diodes are often used. Lasers provide coherent, monochromatic light with a narrow beam, which improves signal stability and allows for accurate measurements in applications like fiber Bragg grating sensors . Superluminescent sources are another option, offering broad-spectrum light with high brightness, useful in distributed sensing and interferometric applications . The choice of light source depends on the sensor type and application:

• Intensity-based sensors: Often use LEDs or laser diodes, where the light intensity changes due to obstruction or reflection are measured .
• Fiber Bragg grating sensors: Typically use laser diodes or superluminescent sources to detect wavelength shifts caused by strain or temperature changes .
• Extrinsic sensors: Use the fiber to transmit light from an external source, which can be LED, laser, or superluminescent, depending on the required precision and environmental conditions . In summary, LEDs, laser diodes, and superluminescent sources are the primary light sources for fiber optic sensors, with the selection guided by the required accuracy, sensing distance, and environmental robustness .