Assume that the optical power transmitted by a 62.5/125 multimode fiber is distributed uniformly across its core. If this fiber is perfectly coupled (i.e., the two fibers are aligned and abutted) to a

The correct answer is B. 36 percent. When power is uniformly distributed across the core, the amount of power that can be captured by the receiving fiber is limited by the ratio of the receiving core's cross-sectional area to the transmitting core's area. Using the core radii (half the core diameter): Area ∝ radius²

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Question

Assume that the optical power transmitted by a 62.5/125 multimode fiber is distributed uniformly across its core. If this fiber is perfectly coupled (i.e., the two fibers are aligned and abutted) to a 50/125 fiber, what is the percent of power that is lost?

Options

A0 percent
B36 percent
C50 percent
D80 percent
E100 percent

How the community answered

(51 responses)

A
8% (4)
B
73% (37)
C
4% (2)
D
2% (1)
E
14% (7)

Explanation

When power is uniformly distributed across the core, the amount of power that can be captured by the receiving fiber is limited by the ratio of the receiving core's cross-sectional area to the transmitting core's area. Using the core radii (half the core diameter): Area ∝ radius². Ratio of received power = (50 μm / 62.5 μm)² = (0.8)² = 0.64. This means 64% of the power is accepted by the smaller 50 μm core. The remaining 36% (1 - 0.64 = 0.36) falls outside the receiving core and is lost. This type of loss - caused by a mismatch in core diameter from a larger transmitting fiber to a smaller receiving fiber - is called intrinsic coupling loss.

Topics

#fiber optic power loss#core mismatch#multimode coupling#optical power calculation

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