L‐Band Mode‐Locked Soliton Fiber Laser Employing an Organic Magnesium Phthalocyanine Pulse Modulator

ABSTRACT Magnesium phthalocyanine (MgPc), a representative material from the phthalocyanine family, has been widely reported to possess strong nonlinear absorption and favorable optical characteristics. In this work, MgPc is utilized as a passive mode‐locking element in an L‐band erbium‐doped fiber laser (EDFL) ring configuration to produce soliton pulses. The MgPc was implanted in a polyvinyl alcohol (PVA) host to form a pulse modulator, yielding a modulation depth of 4.6%. When incorporated into the laser setup, the MgPc‐based modulator enabled stable soliton mode‐locking with a pulse duration of 5.8 ps. The output spectrum was centered at 1595.6 nm after amplification by a dual‐stage amplifier within the ring cavity. The laser operated at a repetition rate of 1.82 MHz, corresponding to the cavity length, and exhibited a high signal‐to‐noise ratio of 72.2 dB. These results confirm that MgPc is a promising passive modulator for ultrafast mode‐locked fiber laser systems operating in the L‐band region.