What are the common refractive indices for the core and cladding in telecom silica fibers, and what does Δn represent?

• A. Core ~1.60–1.62; Cladding ~1.58–1.60; Δn is the sum.
• B. Core ~1.45–1.47; Cladding ~1.44–1.46; Δn is the difference between core and cladding indices (typical ~0.3%).
• C. Core ~1.30–1.32; Cladding ~1.28–1.30; Δn is the product of the indices.
• D. Core ~1.50–1.52; Cladding ~1.48–1.50; Δn is the ratio.

Answer: (B)