What is the outside diameter of single-mode and multimode fiber claddings?

What is the outside diameter of single-mode and multimode fiber claddings?

• A. 100um
• B. 125um
• C. 140um
• D. 150um

Answer: (B)

Cladding diameter is standardized at 125 micrometers for both single-mode and multimode optical fibers. The cladding is the outer glass layer around the core that keeps light guided by total internal reflection, and its diameter is kept consistent (125 μm) so connectors, splices, and components can align properly. The question is asking for the diameter of the claddings themselves, not the protective polymer coating that sits outside the cladding. That coating adds extra thickness, making the overall fiber diameter larger, but the cladding remains 125 μm. The other numbers aren’t the standard cladding size for typical telecom fibers.

Cladding diameter is standardized at 125 micrometers for both single-mode and multimode optical fibers. The cladding is the outer glass layer around the core that keeps light guided by total internal reflection, and its diameter is kept consistent (125 μm) so connectors, splices, and components can align properly. The question is asking for the diameter of the claddings themselves, not the protective polymer coating that sits outside the cladding. That coating adds extra thickness, making the overall fiber diameter larger, but the cladding remains 125 μm. The other numbers aren’t the standard cladding size for typical telecom fibers.