L-band EDFA efficiency enhancement and dynamic range extension by C-band laser injection

In a L-band EDFA, not only the pump power conversion efficiency (PCE) can be improved but also the gain can be clamped by C-band laser injection. On one hand, the injected C-band laser compresses the possible leakage of amplified spontaneous emission (ASE); while on the other hand, the maximum inversion level is limited by the high emission coefficient when the amplified C-Band laser light becomes the dominant pump source, which means that the maximum signal gain is limited so that the gain can be clamped. The numerical and experimental results show that the increment of PCE requires only a certain injected light power, but the clamped gain and the dynamic input power range is dependent on both of the injected wavelength and power.