利用外差法对激光相干合成技术中相位的研究与实现

系统采用并联主振荡-功率放大的相干合成方案，实现光纤激光器的相干合成.外差法是通过实时探测和校正光路中相位的变化，从而使整个系统达到锁相输出的目的.主振荡激光器的波长为1064 nm，输出功率0-100 mW连续可调，光纤相位调制器采用铌酸锂相位调制器.声光移频器的移频量为70 MHz，精度可优于/λ20，相干合成效率≥80%，整个光路为全保偏光路.相位调制器实时控制2路信号的相位差，从而实现整个实验系统的相干合成输出.系统实现闭环控制后，2路光纤放大器的相位差为2π的整数倍，输出光强始终保持最强.该相干合成方案简单易行，性能稳定.

Technical Research of Laser Coherent Combining by Heterodyne

The master oscillator, power amplifier arrangement is experimentally investigated. A high-speed wavefront sensor is introduced to sample the wavefront and actively control the phase state of each individual optical fiber in a high average power fiber laser array, and accordingly the phase-locked output of the whole system is achieved, the wavelength of the master oscillator is 1064 nm and the output power is between 0- 100 mW. Phase noises are controlled by LiNO3 phase modulator. The efficiency of coherent combining light will be above 80 %. In the heterodyne detection control system, the frequency is shifted 70 MHz and the control precision is better than λ/20. Coherent combining of two fiber lasers array is realized. After the control loop is turned on, optical path difference of two fiber amplifiers is 2π, the output intensity is kept at the status of stable high brightness.