Gain clamping in double-pass L-band EDFA

Abstract

Gain clamping in double-pass long-wavelength band erbium-doped fiber amplifier (L-band EDFA) is demonstrated using a ring resonator. This new design provides an improved gain characteristics as well as an efficient tune-ability. The gain is clamped at 11.5 dB with gain variation of less than 0.1 dB from input signal power of -40 to -6 dBm by setting the variable attenuation setting (VOA) at 8 dB. Also, the clamped-gain level can be controlled in the range from 4.7 to 20.9 dB by varying the VOA settings from 0 to 20 dB. However, the proposed gain-clamped amplifier suffers noise figure degradation as compared to open-ring amplifier due to the intense ring laser light, which counter-propagating through the EDF.