Two methods to realize phase controlling of ytterbium fiber amplifiers

In the field of fiber laser coherent combining, phase controlling of ytterbium fiber amplifiers is the most difficult technology in the Master Oscillator-Power Amplifier scheme. Two methods to realize phase controlling of ytterbium fiber amplifiers are studied. One is “climbing hill”, which can optimize the control voltage automatically and the other is “heterodyne detection”, which can realize real-time detection and correction of the phase change. In the experiments, the wavelength of the master oscillator is 1 083 nm and the output power is between 0~100 mW. Phase noises are controlled by LiNO3 phase modulator. The output power of ytterbium fiber amplifiers is between 0~1 W. The fibers are polarizedly maintained. The “climbing hill” control system works at 100 kHz and the control