Exploiting evanescent field interaction with magnetic copper ferrite@reduced functionalized graphene oxide for soliton mode-locked pulses generation

Abstract

This study explored the potential of the CuFe2O4@rFGO nanocomposite as a saturable absorber (SA) material for use in a mode-locked thulium/holmium doped fiber laser (THDFL). The CuFe2O4@rFGO nanocomposite was synthesized using a simple hydrothermal method. To facilitate the coating of the arc-shaped fiber and enable its use as an SA, two varying concentrations of CuFe2O4@rFGO nanocomposite (5 and 10 mg/ml) were prepared. The SA with 5 mg/ml CuFe2O4@rFGO displays nonlinear absorption characteristics with a saturation intensity of 0.26 MW/cm2 and a modulation depth of 36.65%. In contrast, the 10 mg/ml CuFe2O4@rFGO-based SA has a saturation intensity of 1.14 MW/cm2 and a modulation depth of 44.12%. By interacting with the evanescent field of light within the arc-shaped fiber, the CuFe2O4@rFGO nanocomposite enables the generation of stable mode-locked pulses in the THDFL system. The 5 mg/ml CuFe2O4@rFGO-based SA produced mode-locked pulses with a pulse duration of 1.445 ps, a repetition rate of 12.43 MHz, and a signal-to-noise ratio (SNR) of approximately 54 dB. On the other hand, the 10 mg/ml based SA generated mode-locked pulses with a repetition rate of 12.14 MHz, an SNR of 57 dB, and a pulse duration of 1.336 ps. This finding will open new avenues for CuFe2O4@rFGO research in photonics applications.