Graded-index multimode fibers attracted interest in nonlinear regime for their unique nonlinear dynamics characteristics. We report the supercontinuum generation pumped by a superluminescent pulse amplification in graded-index multimode fiber. Efficient supercontinuum was generated and the beam profile cleanup was observed. The speckle characteristics of this supercontinuum is measured and compared to another supercontinuum induced by a homemade mode-locked fiber laser. It is found that the supercontinuum generated by superluminescent pulse amplification attains a smoother speckle structure and lower optical coherence. Our results indicate that the superluminescent pulse amplification could be a more effective means to produce low coherent supercontinuum sources than traditional lasers.
We present an approach for green laser-light generation based on a fiber superluminescent pulse amplification system and frequency doubling to 552 nm with a periodically poled lithium niobate (PPLN) crystal. The SPA system used in the experiment is capable of yielding 6-nm-bandwidth, 10 ns pulsees. The 10-mm-long PPLN with 6.95 μm period and 0.5 mm thick generated high-power green light with single pulse energy up to 5.49 μJ when hte broadband input pulse coherence characteristics of the superluminescent pulse amplifier and the frequency doubling. This generated green light has proved to have low speckle noise and low photon degeneracy.