Reduction of the noise figure at the double-pass erbium doped fiber amplifiers

By using double pass erbium doped fiber amplifiers (EDFA), a higher output signal gain is obtained in comparison to conventional configurations. By this method, transmission range of an optical communication system is increased. However, whilst a higher gain is achieved in double-pass systems with the passing of the signal twice through the erbium doped fiber (EDF), the noise figure increases in parallel with the signal. In this study, the improvements of the noise factor and gain values in double pass C band EDFA are demonstrated. For this purpose, the designed EDFA configurations were simulated and the gain spectrums and noise factors were investigated experimentally by changing the input signal power and signal wavelengths. As a result, it was obtained that whilst the gain increased with the proposed system, the noise factor reduced.