Experimental study on the polarization extinction ratio degradation in high power hybrid fiber amplifier chains employing PM/non-PM Yb-doped fibers

Hybrid fiber amplifier chains employing polarization-maintaining (PM)/non-polarization-maintaining (non-PM) Yb-doped fibers (YDF) were proposed and the polarization extinction ratio (PER) degradation in the amplifier chains was studied experimentally. It was found that the PER increased if the PM YDF was pumped, while the PER decreased gradually if the non-PM YDF was pumped. In addition, it was shown that the hybrid high power fiber amplifier was also coherently combinable experimentally, and it was found that the contrast of pattern captured while using the PM/non-PM hybrid amplifier chains just decreased by 17% compared with only using PM amplifier, which confirmed the feasibility and potential application of the hybrid fiber amplifier chains in the coherent beam combination (CBC) of fiber lasers.

► We propose and proof that hybrid fiber amplifiers are feasible for coherent beam combination.
► We measure the PER of the hybrid amplifiers and compare it with PM amplifiers.
► We study on coherent beam combination of the hybrid amplifiers experimentally.