Microsecond and picosecond pulse generation in an Erbium-doped fiber laser using a polyaniline-reduced graphene oxide (PANI-rGO) based saturable absorber

Abstract A stable Q-switched and soliton mode-locked Erbium-doped fiber laser (EDFL) incorporating polyaniline-reduced graphene oxide (PANI-rGO) as a saturable absorber (SA) is presented. The PANI-rGO was fabricated using liquid phase exfoliation and deposited onto a fiber ferrule using the optical deposition method. By incorporating the PANI-rGO SA into the all-fiber EDFL cavity, stable Q-switching operation was achieved at a pump power of 43.6 mW with a central wavelength of 1562 nm. The repetition rate was tunable from 53.12 kHz to 70.47 kHz by varying the pump power from 43.6 mW to 74.3 mW, while the pulse width decreased from 7.85 µs to 6.25 µs. The maximum pulse energy obtained was 114.4 nJ. By incorporating a 100-meter single-mode fiber (SMF) into the laser cavity, stable mode-locking operation was achieved at a pump power of 157.57 mW. The mode-locked pulses had a central wavelength of 1561.595 nm and a pulse width of 3.86 ps. The repetition rate was 1.8 MHz, and the signal-to-noise ratio (SNR) was 67.67 dB. The findings of this study demonstrate the potential of PANI-rGO as a versatile saturable absorber for generating both Q-switched and mode-locked pulses in fiber lasers.