RCDD Optical Fiber Systems and Testing 1 — Questions and Answers
Question 1: What is the core/cladding diameter of standard single-mode optical fiber as defined by ITU-T G.652?
- 9/125 µm (Correct answer)
- 50/125 µm
- 62.5/125 µm
- 10/125 µm
Correct answer: 9/125 µm
Standard single-mode fiber (ITU-T G.652) has a 9 µm core and 125 µm cladding, which confines light to a single propagation mode for long-distance, high-bandwidth applications.
Question 2: Which multimode fiber type supports the highest bandwidth for short-reach data center applications and is recommended by ANSI/TIA-568 for new installations?
- OM4 or OM5 (50/125 µm laser-optimized) (Correct answer)
- OM1 (62.5/125 µm)
- OM3 (50/125 µm legacy)
- OM2 (50/125 µm)
Correct answer: OM4 or OM5 (50/125 µm laser-optimized)
OM4 (and the newer OM5 wideband) 50/125 µm laser-optimized multimode fiber provides the highest performance for short-reach data center links and is preferred for new installations.
Question 3: What test equipment is used to measure optical fiber attenuation and locate faults or breaks in a fiber link?
- Optical Time Domain Reflectometer (OTDR) (Correct answer)
- Optical Power Meter (OPM)
- Optical Spectrum Analyzer (OSA)
- Visual Fault Locator (VFL)
Correct answer: Optical Time Domain Reflectometer (OTDR)
An OTDR sends light pulses into the fiber and analyzes backscattered reflections to measure attenuation, locate connectors/splices, and identify breaks along the entire fiber length.
Question 4: What is the maximum attenuation allowed for a multimode OM3 fiber link connector per ANSI/TIA-568?
- 0.75 dB per mated connector pair (Correct answer)
- 0.5 dB per mated connector pair
- 1.0 dB per mated connector pair
- 0.3 dB per mated connector pair
Correct answer: 0.75 dB per mated connector pair
ANSI/TIA-568 specifies a maximum attenuation of 0.75 dB per mated connector pair for multimode fiber optical connectors.
Question 5: What does 'chromatic dispersion' cause in single-mode optical fiber?
- Different wavelengths of light travel at slightly different speeds, broadening the pulse (Correct answer)
- Light leaks out of the cladding at sharp bends
- Optical power is partially reflected at connector interfaces
- The fiber's core index of refraction varies with temperature
Correct answer: Different wavelengths of light travel at slightly different speeds, broadening the pulse
Chromatic dispersion occurs because different wavelengths travel at different velocities in fiber, causing pulse broadening that limits bandwidth over long distances.
Question 6: A fusion splice in single-mode fiber typically achieves a loss of approximately:
- 0.02–0.1 dB (Correct answer)
- 0.5–1.0 dB
- 0.3–0.5 dB
- Less than 0.01 dB always
Correct answer: 0.02–0.1 dB
High-quality fusion splices in single-mode fiber typically achieve losses in the range of 0.02 to 0.1 dB, far lower than mechanical splices or connectors.
RCDD Optical Fiber Systems and Testing 1
What is the core/cladding diameter of standard single-mode optical fiber as defined by ITU-T G.652?