Coupled structure for wide-band EDFA with gain and noise figure improvements from C to L-band ASE injection

We propose a novel structure for C plus L-band silica based wide-band erbiu m-doped fiber amplifiers (W-EDFA's), which use backward amplified spontaneo us emission from the C-band EDFA as the pump-mediating injection source for the L-band amplifier unit. Experimental results show gain and noise figure improvements of over 2.6 dB and 0.6 dB, respectively, at -3.5 dBm of L-ban d input signal power, Spatially resolved numerical analysis confirms the pu mp-mediating effect of C-band backward ASE in the L-band EDFA for the gain and noise figure improvement, which also provides better understanding on t he dynamics of C-band injection seed methods.