单段式分布式反馈半导体激光器光学锁相环研究

Optical Phase-Locked Loop of Single Section Distributed Feedback Semiconductor Laser

单段式分布式反馈(DFB)半导体激光器的频率调制相位响应曲线在0.1~5 MHz之间,且具有180°的相位反转,其作为从激光器的光学锁相环(OPLL)结构难以实现锁相。为解决单段式DFB半导体激光器的锁相问题,在单环反馈回路中加入可调超前移相功能电路和可调增益功能单元,并优化相移参数,实现MHz量级线宽DFB激光器相位的锁定。改进后OPLL在锁相状态下的残余相位噪声为0.012rad2,激光器线宽从2 MHz压窄到10kHz。研究了反馈环路的环路增益对OPLL锁相性能的影响,并给出了最优的环路增益控制参数。

The frequency modulation phase response of single section distributed feedback（DFB）semiconductor laser has a 180°phase reversal in 0.1-5 MHz,which makes it difficult for phase locking of optical phase-locked loop（OPLL）when single section DFB semiconductor lasers act as slave lasers.To solve the problem of phase locking in single section DFB semiconductor lasers,we add the adjustable lead phase shift functional circuit and adjustable gain function unit in the single feedback loop,and optimize parameters of phase shift to accomplish phase locking of DFB laser with MHz level linewidth.The residual phase noise of improved OPLL is 0.012 rad2,and the linewidth of DFB laser is compressed from 2 MHz in free-running state to 10 kHz in phase-locked state.In addition,we research the influence of loop gain of the feedback loop on the phase locking performance of OPLL and give the optimized loop gain parameter.