The effect of carboxymethylcellulose host concentration on the performance of mode-locked pulsed laser generation

In this work, the effect of changing the polymer host concentration of a film-based saturable absorber (SA) on the performance of a mode-lock laser in an erbium-doped fiber (EDF) ring cavity was demonstrated. Carboxymethylcellulose (CMC) and graphene oxide (GO) films were used as the polymer host and SA respectively with the CMC-GO films being prepared by the solution casting technique. Fourier transform infrared spectroscopy (FTIR) and field emission scanning electron microscopy (FESEM) analysis showed increased interaction taking place between the polymer host and the SA material as the concentration of the polymer host was increased. X-ray diffraction (XRD) analysis reveals the formation of SA aggregation. Elements in the CMC-GO films were verified using energy dispersive X-ray (EDX) analysis. The modulation depth for 3 mg/mL of CMC and 5 mg/mL of CMC were 4.9% and 4.3%, respectively. Mode-locked pulse operation using 5 mg/mL has a shorter pulse width and broader 3 dB bandwidth than 3 mg/mL. The peak power and pulse energy of 5 mg/mL mode-locked operation were higher than 3 mg/mL. The film with 5 mg/mL shows better stability which was confirmed by the signal-to-noise ratio results. •Mode-locking in an EDFL using a CMC-GO SA.•Concentration of polymer host affects the SA aggregation and in turn the mode-locking performance.•Output solitons with 1.01 ps pulse width and low mode-locking threshold power.•The pulse energy and peak power of 0.234 nJ and 231.7 W at pump power of 149.4 mW.•Stable mode-locking with high SNR of 73–75 dB.