||Stable passive mode-locked fiber lasers(MLFLs) employing graphene saturable absorber (SA) are demonstrated. The graphene were dispersed in de-ionized water by two different dispersants including fluorinated mica clay (Mica) and poly(oxyethylene)-segmented imide (POEM). Using the SA made by graphene dispersed in Mica with thickness and concentration product (TCP) of 36 (μm*wt%), the MLFLs exhibited pulsewidth, 3-dB spectral bandwidth, and modulation depth (MD) of 382 fs, 6.80 nm, and 2.57%, respectively. The graphene dispersed in POEM provides a TCP of 38 (μm*wt%) to make the MLFLs deliver pulsewidth, 3-dB spectral bandwidth, and MD of 422 fs, 6.35 nm, and 1.70%, respectively. In comparison, the graphene SA dispersed by Mica performs a better MLFL pulse quality than that dispersed by POEM. Lastly, for investigating the dispersed uniformity between Mica and POEM, we randomly chose 9 pieces and measured the MLFL performance. The result showed that using the SA made by graphene dispersed in Mica with TCP of 36 (μm*wt%), the MLFLs exhibited pulsewidth of 393±14 fs, By contrast, the graphene dispersed in POEM provided a TCP of 38 (μm*wt%) to make the MLFLs delivered pulsewidth of 442±32 fs. This result reveals that graphene SA film dispersed by Mica exhibited better uniformity than POEM.|
The MLFL of 21-layes CVD process graphene SA showed a pulsewidth of 432.47 fs, a bandwidth of 6.16nm, and a time-bandwidth product (TBP) of 0.323. This result showed that the solution blending process graphene SA exhibited better MLFL performance than CVD.