液芯光纤中基于多线抽运调制的带宽可控平顶布里渊增益谱

Flat-top Brillouin gain spectrum with a controllable bandwidth produceal from multiple-lines pump modulation in liquid-core optical fibers

提出在CS2/CCl4混合介质液芯光纤中利用多线抽运调制技术实现带宽可控平顶布里渊增益谱的方法,理论研究了抽运光谱线间距、谱线强度和芯液介质混合比对布里渊增益谱的影响,得到了带宽可控平顶增益谱的条件.结果表明,采用一个强度或相位调制器,基于单频和多频调制技术产生2—9条抽运光谱线,通过控制谱线间距和各谱线强度比,并改变CS2体积分数,获得了增益带宽在50 MHz—2 GHz范围内可控的平顶增益谱.该方法操作简便、带宽调控范围大,可用于高增益低畸变布里渊放大,满足微弱光信号探测和慢光系统的应用需求.

We present a method of achieving a flat-top Brillouin gain spectrum （BGS） with a controllable bandwidth based on multiple-lines pump modulation in a CS2/CCl4 mixture liquid-core optical fiber. The influences of the pump spectrum separation, the intensity of each spectrum line, and the mixing ratio of core liquid media on the BGS are theoretically investigated, and the conditions of producing the flat-top BGS with an adjustable bandwidth are obtained. Results show that 2-9 spectral lines are generated based on single-frequency and multifrequency modulation using an intensity or phase modulator. The flat-top BGS with bandwidths of 50 MHz-2 GHz are obtained by controlling spectrum separation, the intensity ratio of each spectral line and CS2 volume fraction. This method has advantages of convenient operation and wide bandwidth range. It can be applied in Brillouin amplification with high gain and low distortion, and hence satisfies the requirements of weak signal detection and slow light systems.