# Dispersion Management and Pulse Characterization of Graphene-Based Soliton Mode-Locked Fiber Lasers
## 8 Conclusions  
We have investigated the dispersion management in graphene/PMMA-based soliton mode-locked fiber lasers within anomalous net cavity dispersion ranging from \(-0.033\) to \(-0.121\) ps\({}^{2}\) by controlling the length of SMF-28 in the cavity. Experimental outcomes show that shorter SMF-28 length possesses a net cavity GVD value closer to zero. The proposed system is capable of delivering pulse duration from 710 to 820 fs and maximum pulse energy from 391.47 to 599.52 pJ with the increment of SMF-28 length. On the other hand, the spectral bandwidth becomes wider from 5.6 to 8.2 nm with the decrement of SMF-28 length. In addition, the TBP value can be adjusted to be closer to 0.315 by employing a laser cavity with a higher anomalous effect of GVD. This, in turn, can be enhanced by introducing a longer SMF-28 length to give a stronger soliton effect, but with a drawback of longer pulse duration and lower pulse repetition rate generated. In addition, higher average output power and pulse energy are obtained with longer cavity lengths. In terms of pulse stability, as evaluated from the PER measurement, an irregular pattern of PER value is observed against the length of SMF, whereby the optimum PER value is achieved by using 2 m additional SMF length. From this work, it can be concluded that controlling dispersion behavior is an enabling method to optimize the laser operation that suits certain applications, such as frequency metrology, microscopy, and micromachining.  
Conceptualization, A.F.A., K.Y.L. and M.A.M.; methodology, A.F.A., K.Y.L., M.T.A. and M.A.M.; software, K.Y.L.; validation, A.F.A., K.Y.L. and M.A.M.; formal analysis, A.F.A., K.Y.L., W.M.A., M.T.A., F.D.M. and M.A.M.; investigation, A.F.A., K.Y.L., W.M.A., M.T.A., F.D.M. and M.A.M.; resources, A.F.A., M.T.A. and M.A.M.; data curation, K.Y.L.; writing--original draft preparation, K.Y.L. and W.M.A.; writing--review and editing, A.F.A., K.Y.L., W.M.A., M.T.A., F.D.M. and M.A.M.; visualization, A.F.A., K.Y.L., M.T.A. and M.A.M.; supervision, A.F.A., M.T.A. and M.A.M.; project administration, A.F.A., M.T.A. and M.A.M.; funding acquisition, A.F.A. and M.T.A. All authors have read and agreed to the published version of the manuscript.  
National Plan for Science, Technology and Innovation (MAARIFAH), King Abdulaziz City for Science and Technology, Kingdom of Saudi Arabia, Award Number 3-17-09-001-0007.  
Not applicable.  
This project was funded by the National Plan for Science, Technology and Innovation (MAARIFAH), King Abdulaziz City for Science and Technology, Kingdom of Saudi Arabia, Award Number 3-17-09-001-0007.  
The authors declare no conflict of interest.  
\begin{table}
\begin{tabular}{c c c c} \hline \hline
**Additional SMF Length (m)** & \begin{tabular}{c} **Maximum Average** \\ **Output Power** \\ **(mW)** \\ \end{tabular} & \
\begin{tabular}{c} **Maximum Pulse** \\ **Energy** \\ **(pJ)** \\ \end{tabular} &
\begin{tabular}{c} **Average Output Power** \\ **Slope Efficiencies** \\ **(\%)** \\ \end{tabular} \\ \hline
0.0 & 4.93 & 391.47 & 5.70 \\
0.5 & 5.12 & 419.25 & 5.75 \\
1.0 & 5.01 & 428.33 & 5.67 \\
1.5 & 5.13 & 456.82 & 5.80 \\
2.0 & 5.40 & 484.93 & 6.12 \\
2.5 & 5.26 & 526.15 & 5.93 \\
3.0 & 5.82 & 539.49 & 6.41 \\
3.5 & 5.68 & 567.28 & 6.56 \\
4.0 & 5.99 & 599.52 & 6.76 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Summary of power development and pulse energy evolution of the mode-locked EDFL at different SMF-28 lengths.