2006 Volume 3 Issue 23 Pages 517-521
Gain and noise figure enhancements in an Er/Yb doped fiber amplifier (EYDFA) are demonstrated using a dual-stage amplifier configuration. In comparison to a conventional single-stage amplifier, the gain in this amplifier is enhanced at all wavelengths between 1530 to 1560nm for the input signal powers of -40 and 0dBm. A maximum gain improvement of 7.3dB is obtained at a small signal (-40dBm) wavelength of 1534nm. The noise figure of the design is also enhanced at all wavelengths between 1530 to 1560nm with a maximum reduction of 3.0dB obtained at the small signal wavelength (-40dBm) of 1542nm. The total pump power used in this design is fixed at 140mW. This improvement of gain and noise characteristics is attributed to the efficient pump power distribution within the amplifier and also the addition of a midway optical isolator between the two amplifier stages. The isolator blocks the backward propagating ASE to increase the population inversion at the first stage and thus, enhances the amplifier gain and noise figure. These results show that the usage of a dual-stage configuration with a midway optical isolator is an invaluable consideration when constructing a practical EYDFA.