Passive phase locking of fiber laser based on spatial filtering
基于空间滤波的光纤激光被动相位锁定技术研究

Coherent beam combination of Yb-doped fiber laser array is studied theoretically and experimentally by spatial filtering to passive phase locking. The principle of optical feedback phase locking based on spatial filtering is analyzed, and the relations of Strehl ratio in far field to wavelength and spectrum bandwidth are studied. The coherent beam combination of four Yb-doped fiber amplifier array is achieved experimentally, and stable interference pattern is obtained. The Strehl ratio in far field is 0.77. In the output spectrum, the bandwidth of single longitudinal mode is about 9.1 GHz consistent with the theoretical calculation.