This paper proposes a scheme to lock the frequency difference between two distributed feedback (DFB)laser diodes with high stability and wide bandwidth.The locked wide bandwidth with high stability ranges from 50MHz to 11GHz.An error frequency is first evaluated by measuring the net difference of the targeted frequency and the beating frequency between two lasers.Second,based on the proportional-integral-derivative (PID) control algorithm,the feedback control of temperature and current of one laser is implemented to coarsely and finely tune the beat frequency between two lasers as well as the net difference,respectively.The experimental result indicates that the stability of the locked frequency difference within the wide bandwidth is below 5MHz RMS under a two-hour measurement,which approaches the theoretical limitation.%提出了一种可用于两台半导体分布反馈(DFB)激光器的高稳定宽带锁频方案,高稳定光频锁定范围可覆盖50MHz至11GHz.通过测量和计算得出两台DFB激光器的光频差与目标频率之间的误差,然后基于比例-积分-微分(PID)控制算法反馈控制其中一台DFB激光器的温度和电流,分别粗调和微调其输出光频率,最终实现两台激光器的光频差锁定.实验结果表明,在连续工作2小时内宽带锁频稳定度的均方根误差优于5MHz,接近理论极限.
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