Fiber Optic Test Sources

My previous quiz focused on power meters and how they are used to make basic measurements. To measure loss, you need a test source in addition to a power meter. Are you familiar with the sources used for fiber optic testing? More information on optical power can be found in the Fiber Optics Association Guide at

1. A test source for fiber optic cables uses a(n) _______ or a(n) _______ to create light to couple into the fiber. (Choose two.)

Correct Answer: LED
Correct Answer: Laser

2. The light source must be similar to the _______ to be compatible with the fiber being tested.

Correct Answer: Network transmitter

3. The source reference power for “0 dB” when making loss measurements is set at _______.

Correct Answer: The output of the reference test cable used for testing loss

4. Since the fiber attenuation varies with _______, a source of similar _______ must be used for testing. (Choose two.)

Correct Answer: Wavelength

5. Multimode fiber is tested with a(n) _______ source at _______.

Correct Answer: LED, 850 or 1,300 nanometer (nm) wavelength

6. The _______ of a multimode test source can cause big variations in the loss measured.

Correct Answer: Modal distribution

7. Sources for multimode testing should use a mandrel wrap on the launch cable to _______.

Correct Answer: Condition the modal distribution of the launch

8. The mandrel wrap used in multimode testing to create standard test conditions will in addition reduce the loss measured significantly.

Correct Answer: True

9. Single-mode fiber testing requires a(n) _______ source at _______ wavelength.

Correct Answer: Laser, 1,310 nm and/or 1,550 nm

10. To allow accurate tests, the source must ________.

Correct Answer: All of the above