Fig. 1. Experimental setup of two ultrafast laser channels coherent polarization beam combination. CFBG：chirped fiber Bragg grating; Pre-amp: pre-amplifier; HWP: half-wave plate; PBS: polarization beam splitter; QWP: quarter-wave plate; L1-L4: lens; M1-M4, high-reflection mirror; PBC: polarization beam combiner; PD: photodiode; PM: power meter; (b) output spectrum and (c) pulse width of the seed laser

Fig. 2. (a) Normalized temporal intensity fluctuation before and after phase locking (open loop and closed loop); (b) Power spectral density curves at the open and closed loop; system combined beam profile in (c) -(e) open loop and (f) closed loop

Fig. 3. Combining efficiency at different output powers

Fig. 4. (a) Output spectra and (b) autocorrelation trace of the compressed pulse of single channel and combined beam at the highest power