采用掺铒光纤在L-波段的放大自发辐射(ASE)构成的宽带光信号源在光纤传感、器件测试等方面有着广泛的应用需求,而抽运转换是制作这种光源的关键技术之一。基于C-波段放大自发辐射对L-波段信号具有二次抽运作用的机理,在光纤的一端采用Sagnac反馈环将输出的C-波段放大自发辐射反馈回到掺铒光纤中,这些被反馈的C-波段放大自发辐射像注入的信号光一样消耗上能级粒子数而受到放大并沿光纤的同一方向传输,同时成为L-波段放大自发辐射的抽运源。由于Sagnac反馈环减少了泄漏的C-波段放大自发辐射功率,因而抽运转换效率大大提高。实验中,在不加平坦滤波器的情况下,在125 mW 980 nm抽运光输入时输出L-波段放大自发辐射宽谱功率达到14 dBm,抽运转换效率(PCE)达到20%,1 dB带宽达到31.1 nm(1568.9～1600 nm),获得了高转换效率且宽带平坦的L-波段放大自发辐射谱输出。

Optical wideband source of L-band amplified spontaneous emission (ASE) from erbium doped fiber has extensive application in fiber sensors and device testing; here the pump power conversion is one of the key technique. In this work, based on the secondary pumping mechanism by C-band power for L-band signal, a Sagnac loop is used to feed-back the output of C-band ASE, the reflected C-ASE propagates along single direction in the fiber and is amplified in expending inversion population, so that the utility of pump power for L-band ASE is increased. Experimentally, the total output power was 14 dBm at 125 mW 980 nm pumping i.e. pump power conversion efficiency up to 20% was achieved. Without gain flatten filter, the 1 dB bandwidth was 31.1 nm (1568.9～1600 nm), so that high pump conversion efficiency and broad L-band ASE source was demonstrated.