Carboxyl graphene oxide solution saturable absorber for femtosecond mode-locked erbium-doped fiber laser

Lv Rui-dong¹, Li Lu², Wang Yong-gang^{1, †}, Chen Zhen-dong¹, Liu Si-cong¹, Wang Xi³, Wang Jiang¹, Li Yong-fang¹

(color online) Mode-locked pulse state: (a) optical spectrum, (b) autocorrelation traces, (c) pulse trains of oscilloscope, and (d) radio-frequency spectrum.