We report an all-fiber high power,single frequency large-mode area （LMA） linearly polarized ytterbiumdoped fiber amplifiers （YDFA） module,which is based on the master oscillator multi-stage power amplifiers （MOPA）.The maximum output power is 43.8 W at a wavelength of 1064 nm when 60-W launched pump light is coupled,with high slope efficiency of 88%,polarization extinction rate （PER） 17.2 dB and nearly diffraction-limited beam quality （M 2 1.1）.
We experimentally demonstrate the phase locking of a two-dimensional （2D） array of four fiber lasers using an improved self-imaging resonator with a spatial filter. The high visibility interference round stripes of the coherent beam profile are observed. The coherent output power of the fiber array exceeds 134 W. Tile entire system operates quite stably, and no thermal effects observe in the spatial filter, indicating that the coherent output power can be increased using this method.
The influence of the amplitude ratio between the two THz pulses on two-dimension THz spectroscopy(2DTS)has been studied theoretically via a classical method in which the expressions for the second-order nonlinearity were derived using perturbation approach,and the THz pulses were not treated as a delta function.Three types of nonlinear sources i.e.,anharmonicity,nonlinear damping,and nonlinear coupling,are considered in a single mode system.The simulation results demonstrated that the amplitude ratio had a notable influence on the 2DTSs,and different sources have different influences.This study is promising for guiding future experiments.
Jiangsheng HuJinsong LiuHuquan LiKejia WangZhengang YangShenglie Wang
