Tapered Yb3+-doped photonic crystal fiber for blue-enhanced supercontinuum generation

The absorption spectrum of the Yb3+-doped photonic crystal fiber covers from 770 nm to 980 nm. A less flatness broadband continuous spectrum and a short peak are generated in the uniform Yb3+-doped photonic crystal fiber. Supercontinuum from 388 nm to 1590 nm is received in the tapered Yb3+-doped photonic crystal fiber, which covers almost two octaves, generating an ultra flat (7 dB) continuous spectrum coming from 926 nm to 1554 nm in the long waveband, and receiving a 62 nm width, high and violet peak from 388 nm to 450 nm in the purple waveband by femtosecond pulse. The up conversion efficiency of pump power in tapered Yb3+-doped photonic crystal fiber is up to 59.4%, while the uniform is only 6.3%.