Utilization of magnesium phthalocyanine for pulse modulation in mode-locked soliton lasers

Magnesium phthalocyanine (MgPc), a prominent member of the phthalocyanine family, has been previously reported to exhibit strong nonlinear absorption and excellent optical properties. In this study, MgPc is employed as a mode-locking device in an erbium-doped fiber laser ring resonator, enabling the emission of soliton pulses. The MgPc was incorporated into a polyvinyl alcohol matrix to form a saturable absorber (SA), achieving a modulation depth of 5% and a saturation intensity of 23MW/cm². Integration of the MgPc SA into the ring cavity produced in a stable mode-locked soliton pulses with a pulse duration of 1.1 ps, within a pumping range of 55.88 to 118.48 mW. The generated pulse train operated at an output spectrum centered at 1564.05 nm and had a repetition frequency of 1.795 MHz, corresponding to the cavity length, and exhibited a high signal-to-noise ratio of 71.5 dB. These results demonstrate that MgPc is an effective passive modulator for ultrafast laser systems based on mode-locking.