The standard outside diameter of the fiber cladding is 125 um. Which component does this refer to?

The standard outside diameter of the fiber cladding is 125 um. Which component does this refer to?

• A. Cladding
• B. Core
• C. Buffer
• D. Jacket

Answer: (A)

Light is guided in a core surrounded by cladding that has a lower refractive index, keeping the light trapped by total internal reflection. The core is the tiny central region where the light travels, while the cladding forms a surrounding layer with a standard outer diameter of 125 micrometers. That 125 μm size is a fixed spec for the cladding, which is why this measurement points to the cladding itself. The core is much smaller in diameter—on the order of 8–10 μm for single-mode fibers or about 50–62.5 μm for many multimode fibers—while the buffer and jacket are protective layers outside the cladding that add even more to the overall fiber diameter. So the 125 μm outer diameter corresponds to the cladding.

Light is guided in a core surrounded by cladding that has a lower refractive index, keeping the light trapped by total internal reflection. The core is the tiny central region where the light travels, while the cladding forms a surrounding layer with a standard outer diameter of 125 micrometers. That 125 μm size is a fixed spec for the cladding, which is why this measurement points to the cladding itself. The core is much smaller in diameter—on the order of 8–10 μm for single-mode fibers or about 50–62.5 μm for many multimode fibers—while the buffer and jacket are protective layers outside the cladding that add even more to the overall fiber diameter. So the 125 μm outer diameter corresponds to the cladding.