Enhancement of power conversion efficiency for an L-band EDFA with a secondary pumping effect in the unpumped EDF section

A novel structure, which utilizes detrimental backward amplified spontaneous emission as a secondary pump source is suggested for a silica-based fiber amplifier, operating at a wavelength range from 1570 to 1610 nm. By using the secondary pumping effect from the strong, wasted 1550-nm band amplified spontaneous emission power in the unpumped section of the erbium-doped fiber, it was possible to achieve a considerable improvement in power conversion efficiency, increasing small-signal gain by more than 4 dB. The suggested pump structure was also shown to be useful in overall conversion efficiency improvement for L-band EDFA's, regardless of pump wavelength choice.