High efficiency supercontinuum generation using ultra-long Raman fiber cavities.

Supercontinuum generation in a multi-fiber ultra-long Raman fiber laser cavity is experimentally investigated for the first time. We demonstrate significantly enhanced spectral flatness and supercontinuum generation efficiency using only conventional single mode silica fiber. With a pump power of only 1.63W a approximately 15 dB bandwidth >260 nm wide (from 1440 to >1700 nm) supercontinuum source is reported with a flatness of <1 dB over 180 nm using an optimised hybrid TW/HNLF cavity. We address the dependence of the supercontinuum spectrum on the input pump power and ultra-long Raman cavity.