Gain‐clamping in L‐band zirconium–erbium co‐doped fiber amplifier with FBG based lasing control

Abstract

In this study, gain clamping performance in an L-band zirconium-erbium co-doped fiber amplifier (Zr-EDFA) with a very short length of heavily doped fiber and FBG based lasing control structure was presented. A simple gain clamping design based on a symmetrical narrow band C-band fiber Bragg grating (FBG) pair addition was used in the L-band Zr-EDFA with bidirectionally pumping scheme. An L-band gain of higher than 25 dB was obtained with a maximum noise figure (NF) of 5 dB in the conventional Zr-EDFA design which was higher than the previous results obtained with forward pumping scheme. When a couple of narrow band FBGs at Bragg reflection wavelength of 1542 nm are used as the lasing mechanism for gain clamping in L-band operation, small signal gain of Zr-EDFA decreases, but on the other hand, the gain is clamped at almost 15.5 dB with a flattened gain spectrum along a dynamic range of 25 dB for the signal input powers between À30 and À5 dBm with the expense of 1.5 dB NF penalty.