Dark pulse generation in long cavity erbium-doped fiber laser with iron phthalocyanine absorber

Abstract

In this paper, we report the first experimental generation of domain-wall (DW) dark pulses from a passively mode-locked Erbium-doped fiber laser by means of iron phthalocyanine (FePc) as the saturable absorber (SA). The FePc SA, with a modulation depth of 8.1 %, was fabricated on a fiber ferrule platform by embedding FePc particles into a polyvinyl film using a drop-casting technique. The DW dark pulses were generated at dual wavelengths of 1591.8 nm and 1592.9 nm, due to cavity birefringence, while dark pulse formation resulted from cross-phase coupling between these wavelengths. The repetition rate and negative pulse width were measured to be approximately 1.94 MHz and 93.2 ns, respectively, within a pump power range of 90.4 mW to 150.76 mW. The laser achieved a maximum pulse energy of 3.95 nJ at a pump power of 150.76 mW. The signal-to-noise ratio of the fundamental frequency was 63.1 dB, indicating promising stability.