Investigation and performance evaluation of filter aided configurations for erbium doped fiber optical amplification system

Various possible configurations of EDFA's namely Single Pass (SP) EDFA, Double Pass (DP) EDFA, Double Pass with Filter (DPF) EDFA, Triple Pass with Filter (TPF) EDFA and finally Quadruple Pass with Filter (QPF) EDFA are designed. DPF EDFA is an upgraded and enhanced version of DP EDFA configuration designed by using an optical filter in cascade. This filter has been designed with an optimal set of internal parameters namely center wavelength, bandwidth and depth. TPF and QPF EDFA configurations have also been designed. It is observed that in absence of upconversion, maximum Figure Of Merit (FOM) of about 40.35 dB is achieved in QPF EDFA configuration. With upconversion mechanism enabled the FOM of QPF EDFA reduces to only about 37.45 dB thus making QPF EDFA configuration suitable for practical applications. QPF and TPF EDFA had minimum gain ripple thus can be used in WDM applications, where flattened gain spectrum is an important requirement. The configurations offered here are less bulky with only one filter used instead of two as was the case in earlier configurations. QPF EDFA designed in this work has a reduced noise figure of about 4.85 dB at smaller lengths of EDFA of about 4.5 m and lower pump powers of about 90 mW. This configuration has highest sensitivity with the capacity to detect minimum signal power of −41.6 dBm. The QPF EDFA has an improved gain with reduction in noise figure, therefore QPF EDFA can be used as a preamplifier, to improve the sensitivity of receiver.