Wideband optical frequency comb generation using a fiber re-circulating loop cascaded with a spectrum expander including highly nonlinear fiber

A wideband optical frequency comb (OFC) generator using a fiber re-circulating loop (FRL) including phase modulator and amplifier, cascaded with spectrum expander containing high-power erbium-doped amplifier highly nonlinear (HNLF) is proposed experimentally demonstrated, in which the FRL used as source to generate seed lines, then generated lines are extended four-wave mixing HNLF. Only one stage expander, stable 20-GHz 201 within 30-dB power deviation, spanning 40-nm bandwidth, achieved. The results show that HNLF has unique ability broaden output from FRL. In addition, an dramatically broadened, may be predicted by optimizing gain dispersion of or configuration both.