Fiber optic sensors do not directly output voltage; instead, they detect electrical voltage or current through optical effects and convert it into light signals that can be measured electronically.

How Fiber Optic Sensors Measure Voltage

Fiber optic sensors are primarily optical devices that use light transmitted through optical fibers to sense physical or electrical quantities. For voltage measurement, specialized fibers are doped or designed to respond to electric fields. The nonlinear optical effects in these fibers cause changes in the polarization, phase, or intensity of light as a function of the applied voltage or electric field, which can then be converted into an electronic signal for measurement (Wikipedia) .

Fiber Optic Current and Voltage Sensors

Some fiber optic sensors, particularly fiber optic current sensors, operate based on the Faraday Effect, where a magnetic field generated by an electrical current rotates the polarization of light traveling through the fiber. By measuring this rotation, the sensor can determine the magnitude and direction of the current. Voltage can be indirectly measured by monitoring the current through a known resistance or using specially designed fibers sensitive to electric fields (GTRIC) .

Advantages Over Traditional Sensors

• Electrical isolation: Since the sensing element is optical, there is no direct electrical connection, making fiber optic sensors safe in high-voltage environments or explosive atmospheres.
• Immunity to electromagnetic interference (EMI): Optical signals are unaffected by nearby electrical noise, ensuring accurate voltage or current measurements.
• Remote sensing capability: Fiber optic sensors can transmit signals over long distances without degradation, allowing voltage monitoring in inaccessible or hazardous locations (Wikipedia) .

Signal Conversion

The optical signal generated by the fiber in response to voltage or current is typically converted into an electronic signal using a photodetector or optical receiver. The resulting electronic output can be expressed as a voltage proportional to the measured electrical quantity. The exact voltage output depends on the sensor design, amplifier, and calibration, rather than a fixed standard voltage inherent to the fiber itself (KEYENCE) .

Summary

Fiber optic sensors do not produce a fixed voltage like conventional electrical sensors. Instead, they sense voltage or current optically and convert the optical response into an electronic signal, which can then be measured as a voltage. This approach provides high safety, EMI immunity, and flexibility for monitoring electrical systems in challenging environments.