C+L波段宽带增益平坦铋基掺铒光纤放大器的设计

基于光纤放大器增益谱的宽带平坦化发展需要,设计了一个两段铋基掺铒光纤(Bi-EDF)级联并携带一个C波段(1 530~1 565 nm)宽带光纤布拉格光栅(FBG)的双通结构型铋基掺铒光纤放大器(Bi-EDFA),从理论上研究了其对输入信号的放大特性。研究表明:FBG的引入可以使C和L波段(1 570~1 620 nm)信号分别经历不同长度Bi-EDF的双向传输,各自获得高增益放大,实现增益谱的宽带平坦化。在200 mW的1 480 nm双向对称泵浦下,第一级和第二级Bi-EDF长度分别为50 cm和170 cm时,对于波长间隔为2 nm、每路功率为-30 dBm的56路C+L波段信号的输入,Bi-EDFA高于30 dB的增益带宽达到了90 nm(1 530~1 620 nm),平均增益为35.7 dB,增益起伏仅为2.3 dB。同时,噪声系数得到明显改善。研究结果对于研制具有宽带、增益平坦的C+L波段Bi-EDFA具有实际指导意义。

Design of C+L-band broad gain-flattened bismuth-based erbium-doped fiber amplifier

In order to meet the developing needs of broad amplification as well as gain-flattened operation for fiber amplifier,a double-pass structure of bismuth-based erbium-doped fiber amplifier(Bi-EDFA) with the incorporation of C-band(1 530-1 565 nm) broad fiber Bragg grating(FBG) in between the two cascaded segments of bismuth-based erbium-doped fiber(Bi-EDF) was designed,and the amplifying performances of Bi-EDFA were presented theoretically.The results indicate that a broad amplification and gain-flattened spectrum can be achieved with the aid of the simultaneously obtained high gain of the C-band and L-band(1 570-1 620 nm) signals due to their experiencing a different length bi-directional transmission in Bi-EDF after the incorporation of FBG.A gain bandwidth of 90 cm with average gain 35.7 dB and gain variation of approximately ±2.3 dB within the wavelength range from 1 530 nm to 1 620 nm are obtained under the conditions of the 1 480 nm bi-directional symmetrical pumping with pump power of 200 mW,the first and second Bi-EDF length of 50 cm and 170 cm,and 56-channel signals of C+L band with interval of 2 nm and each power of-30 dBm are inputted simultaneously.Meanwhile,the noise figure of Bi-EDFA is improved evidently.The theoretical studies will provide practical significance for a new design of C+L-band Bi-EDFA with broad and flattened gain.