Polarization self-selection in a coherent beam combination system with an all-optical feedback loop.

Polarization self-selection in passive phasing of four fiber amplifiers with an all-optical feedback loop is demonstrated. The polarization extinction ratio (PER) of the combined beam is increased, and the polarized direction is selected with the use of a polarization-maintaining (PM) isolator and some non-PM components. The best visibility of the interference patterns is observed at 95.2% and in the largest increment in the PER of the combined beam up to 7.4 dB. Results show that all PM components are unnecessary in the coherent beam combination with an all-optical feedback loop, whereas non-PM components have good potential to achieve high output power.

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