What happens when a laser light source is used to test fibers?

Using a laser light source to test fibers is primarily concerned with the modulation of the light signal for successful identification and testing of optical fibers. The correct option highlights that a 2 kHz modulation creates a test signal that can be effectively detected by optical fiber identifiers. This modulation frequency is significant because it allows for clear differentiation between the test signal and any background noise that may be present in the environment.

This detection ability is essential for ensuring accurate testing of the fiber's integrity and performance. Higher modulation frequencies, like 2 kHz, are often leveraged in fiber testing because they can enable more sophisticated detection techniques that differentiate the signal from potential interference, making this method suitable for effectively identifying and analyzing the optical fibers during testing.

Conversely, while a 1 kHz modulation could also provide a basic signal, it may not be as effective for certain identification tasks, and maintaining a constant power level does not specifically address the detection needs of optical fiber identifiers. Likewise, visual inspection can identify defects but does not utilize the laser's properties for testing fiber integrity in terms of transmission quality or signal degradation.