Which of the following transmitter light sources has a MINIMUM bandwidth of 4700 MHz/km (EMB) at 850 nm">

Question

Options

• AOM1 (62 50/125 multimode)
• BOM2 (50/125 multimode)
• COM3 (50/125 laser optimized multimode)
• DOM4 (50/125 laser optimized multimode)

• A
  5% (1)
• B
  5% (1)
• C
  16% (3)
• D
  74% (14)

Explanation

OM4 (50/125 laser-optimized multimode) is correct because its specification requires a minimum effective modal bandwidth (EMB) of 4700 MHz·km at 850 nm, making it the highest-performing standard multimode fiber and the only one meeting that threshold. OM1 (62.5/125) is wrong because it is an older, wider-core fiber with a much lower bandwidth rating (around 200 MHz·km overfilled launch bandwidth) and is not laser-optimized. OM2 (50/125) is wrong because, while it uses the same core diameter as OM3 and OM4, it lacks laser optimization and only achieves around 500 MHz·km. OM3 is wrong because, although it is laser-optimized like OM4, its minimum EMB is 2000 MHz·km at 850 nm - less than half the OM4 requirement. Memory tip: rank the OM grades by bandwidth in ascending order - OM1 is lowest, OM4 is highest - and remember that 4700 MHz·km is the OM4 number by associating "4" in OM4 with "4700."

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