Flat supercontinuum generation by nanosecond pulses pumped

Microchip-laser-pumped supercontinuum (SC) is successfully generated through a 30-m long photonic crystal fiber (PCF). The spectra bandwidth of SC is 850 nm spanning from 550 nm to 1300 nm. The -15dB-flat bandwidth is 400 nm spanning from 600 nm to 1000 nm. It is easy to achieve a much more flat SC with the sacrifice of spectra bandwidth. A detailed simulation is carried out to help us understand more about the supercontinuum generation process. The primary mechanism of spectral broadening is identified as parametric four-wave mixing (FWM) combined with stimulated Raman scattering (SRS). These findings also demonstrate an effective way to generate a flat supercontinuum laser source.