Investigation and performance evaluation of DFB- (SP) EDFA configuration with optimum intrinsic EDFA parameters

Distributed feedback laser (DFB) along with erbium doped fiber amplifier (EDFA) have become the key components of the rapidly growing WDM and cable TV optical communication systems. DFB is used in most of the networks because of narrow linewidth, low chirp and low relative intensity noise (RIN). This paper has presented an investigation for influence of DFB laser on the gain behaviour in an EDFA which is pumped by 980 nm. Various DFB laser rate equation parameter sets have been extracted with different threshold current values and their suitability to be used in conjunction with EDFA has been investigated in the distributed feedback laser- single pass erbium doped fiber amplifier (DFB- (SP) EDFA) setup. The permissible range of operation of DFB laser and EDFA was identified. Impact of slope efficiency on DFB lasers of different threshold current values was observed. Also, effect of linewidth on EDFA gain spectrum is investigated. This study enabled to identify optimum parameter set for EDFA in the SP configuration setup with gain (G), figure of merit (FOM) and flattened gain spectrum ( δ G λ ) adopted as the performance evaluation parameters. This work offers a DFB- (SP) EDFA setup where highest G obtained among all the laser samples is 11.05 dB, FOM is 6.18 dB, δ G λ is 10 nm over an operating wavelength range of 1540 nm to 1550 nm. Further an optimum intrinsic EDFA parameter set has been identified which showed improvement in the aforementioned setup where improvement in gain is 16.68 dB at higher FOM of 11.54 dB. Moreover, δ G λ has been enhanced to 20 nm in the wavelength range from 1540 to 1560 nm. A 23 channel DWDM system has been setup where it was observed that longer optical link lengths are obtained with EDFA Opt as compared to EDFA Initial.