Erbium-doped fiber amplifiers:

  • The active medium in an optical fiber amplifier consists of a nominally 10 to 30 m length of optical fiber that has been tightly doped with a rare-earth element such as Erbium (), Ytterbium (), Neodymium () or Praseodymium (). The host fiber material can be either standard silica, a fluoride-based glass or a multicomponent glass.
  • The operating regions of these devices depends on the host material and the doping Flourozirconate glasses doped with or  are used for operation in the 1300-nm window, since neither of these ions can amplify 1300 nm signals when embedded in silica glass.
  • The most popular material for long haul telecommunication application is a silica fiber doped with Erbium, which is known as Erbium-doped fiber amplifier or EDFA.
  • The operation of an EDFA by itself normally is limited to the 1530 to 1560 nm region.

Features of EDFA


  • Active medium is created by erbium (), ytterbium (), neodymium (), praseodymium( ).
  • DFA can pump device at several different
  • Low coupling
  • Constant






Example 8.3.1 :An EDFA amplifier produces   = 27 dBm for an in out level of 2 dBm at 1542 nm.

  1. Find the amplifier
  2. What is the minimum pump power required ? [Jan./Feb.-2007, 10 Marks] Solution : i) Amplifier gain


                                                                                                  … Ans

  1. ii) Pump power Pp, in






Therefore minimum pump power should be 27 dBm.                                             … Ans