In this paper a combined serial–parallel hybrid fiber amplifier (SP–HFA) in the C+L–band is investigated and simulated via OptiSystem 7. The gain spectra of the C+L–band are flattened by optimizing the coupling ratio of the input signal power. The gain bandwidth of 62.5 nm from 1530 nm –to– 1592.5 nm within the gain variation of about 2.68 dB is achieved with small input signal power of –20 dBm. In addition, the proposed design produced several advantages over conventional P-HFA, such as; increased flat gain bandwidth by 2.5 nm, constant splitting ratio of 0.7 for small and large signal regions, high saturation gain (wide dynamic range) in the L–band window.
