High-Power Narrow-Band and Polarization-Maintained All Fiber Superfluorescent Source

In this letter, we experimentally investigate the near-diffraction-limited power scaling ability of a high-power narrow-band and polarization-maintained all fiber amplifier chain fed by selecting a small portion of a broadband superfluorescent source. By amplifying the filtered laser based on master oscillator power amplifier configuration, a record power of 800 W is achieved in this type of monolithic amplifier with a slope efficiency as high as 87.7% in the final amplifier and M² factor of ~1.3. The polarization extinction ratio (PER) and 3-dB bandwidth (FWHM) are measured to be >12 dB and 0.2 ± 0.02 nm, respectively. Further power scaling the amplifier chain, we show that the mode instability effect is occurred, which causes sharply deteriorations of the beam quality and PER. Besides, we show that the influence of self-phase modulation effect and four-wave-mixing effect should also be carefully considered to ensure high portion of narrow-band energy when further enhances this kind of narrow-band architecture.