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Fiber Optics Flashcards

7 cards from real VDV practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Which standard defines the performance requirements for 50/125 µm multimode fiber used in OM3 and OM4 applications?

    Answer: TIA-492AAAC / ISO 11801

    TIA-492AAAC (aligned with ISO 11801) specifies the laser-optimized 50/125 µm fiber characteristics for OM3 and OM4 categories.

  2. What is the function of the cladding in an optical fiber?

    Answer: Provide a lower refractive index to contain light within the core

    The cladding has a slightly lower refractive index than the core, enabling total internal reflection to confine light transmission.

  3. A fiber optic link shows a sudden high-loss event at 500 m on an OTDR trace. What does this most likely indicate?

    Answer: A fiber break or severe bend at that location

    A sudden high-loss event (non-reflective or reflective spike) at a specific distance indicates a fiber break, sharp bend, or crush point.

  4. What is 'return loss' (RL) in fiber optic connectors?

    Answer: The measure of reflected light back toward the source at a connector

    Return loss measures how much light is reflected back toward the source; higher RL values (e.g., >55 dB) indicate less reflection, which is better for system performance.

  5. Which wavelength window is most commonly used for single-mode fiber transmission in long-haul telecom?

    Answer: 1550 nm

    The 1550 nm window has the lowest attenuation (~0.2 dB/km) in silica fiber and aligns with EDFA amplifier gain bands, making it standard for long-haul transmission.

  6. What is the correct cleaning procedure before mating fiber optic connectors?

    Answer: Clean with IPA using lint-free tools, then inspect with a fiber scope

    Proper cleaning uses isopropyl alcohol with lint-free tools followed by inspection under a fiber scope to confirm the end-face is clean before mating.

  7. In a wavelength-division multiplexing (WDM) system, what is being multiplexed?

    Answer: Multiple optical signals at different wavelengths on one fiber

    WDM combines multiple optical channels at different wavelengths (colors) onto a single fiber, greatly increasing the fiber's transmission capacity.