基于Talbot效应的激光二极管阵列外腔锁相

External Cavity Phase-locked of a Laser Diode Array Based on Talbot Effect

对基于Talbot效应的激光二极管(LD)阵列外腔锁相进行了理论和实验研究。在腔内各阶超模近场分布的基础上,在腔外加会聚透镜,在其焦平面上得到了同相模和异相模的远场分布。根据同相模和异相模在Talbot腔中的分布特性,提出ZT/2腔(指腔长的往返长度)进行外腔锁相时的理想腔长。由于ZT/2腔内是异相模振荡,远场图像为双瓣模,这时如果让外腔镜在慢轴方向倾斜角度α,让反馈回阵列的同相模和异相模成像位置各发生d/2的偏移,恰好可以选择同相模而抑制异相模。最后采用ZT/2腔对LD阵列的外腔锁相进行了实验研究,并在外腔镜不偏转和偏转角度α时分别观察到同相模和异相模的锁相现象。经过分析计算,同相模锁相时,其远场单瓣模的发散角约为1.96 mrad。

Phase locking of a laser diode（LD） array in an external cavity based on Talbot cavity was studied theoretically and experimentally. On the foundation of near field distributions of supermodes,far field distributions of in-phase mode and out-of-phase mode were obtained in the focal plane by using diffraction lens outside of the cavity. According to the distributions of the in-phase mode and the out-of-phase mode in the Talbot cavity, it can be seen that ZT/2 cavity （the round trip） is preferable for phase locking of LD arrays. But ZT/2 cavity only allows out-of-phase mode oscillating, and the far field distribution is double lobes,which is not suitable in most cases. If the external mirror is tilted by an angle of α, the diffraction images of in-phase mode exactly coincide with the apertures, while out-of-phase mode is imaged exactly in between the apertures,resulting in high loss. Distributions of in-phase mode and out-of-phase mode are obtained in the experiment for both cases,and the divergence angle of far field single lobe is 1.96 mrad.