基于迈克尔逊型耦合腔光纤激光器相干合成的理论与实验研究

为使光纤激光器在自由空间中进行有效的相干合成,提出了耦合臂上带有会聚透镜的迈克尔逊型耦合腔,并将外腔配置为f－f结构以增强内部反馈.利用高斯光束的ABCD定律分析了外腔的传输特性,详细研究了外腔偏离f－f结构对相互注入耦合效率的影响,指出输出光纤端面与透镜前焦平面的偏差是影响反馈耦合效率的关键因素.基于此特别设计的迈克尔逊型耦合腔,实验上实现了两路光纤激光的有效相干合成.当透镜被移走时,阵列输出功率下降为原始值的78.5％,且相干态变得不稳定.

Theoretical and Experimental Study on Coherent Combining of Fiber Lasers Using a Michelson-type Coupled Cavity

To make fiber lasers combined coherently and efficiently in free space, the Michelson-type coupled cavity with convergent lenses in its arms was proposed, and an f-f arrangement was configured to improve internal feedback. The characteristics of the cavity were studied with the ABCD law of Gaussian beam, and the particular effects of deviations from the f-f arrangement were analyzed, then it is found that the deviation of output fiber end and front focal plane of the lens is the key factor to affect the feedback coupling efficiency. And, efficiently coherent combining of two fiber lasers with this special designed Michelson-type coupled cavity was demonstrated. When the lenses are taken away, the output power of coherent array decrease to nearly 78.5% of its original value, and the coherent state become less stable compared to the state of with lenses.