Question

Which of the following elements is doped to a fiber amplifier in an optical fiber communication system?

• A. Tm
• B. Yb
• C. Er
• D. Nd

Hint:

Erbium doped fibre amplifiers are the standard amplifiers in optical fibre communication.

Answer 1

The Correct Option is C

Step 1: Link wavelength to ion.
Best fibre transmission is near 1550 nm. The erbium ion $\text{Er}^{3+}$ has an energy transition that matches that wavelength.

Step 2: Pick.
Hence the amplifier is the erbium doped fibre amplifier. Tm, Yb and Nd serve other uses.

Final Answer:
Option (C). \[ \boxed{\text{Er}} \]