▎ 摘　　要

In this paper, we report our results on the use of patterned graphene on SiN waveguides inside an erbium doped fiber ring laser cavity for passive mode locking. We confirm the dominant influence of graphene over non-linear polarization rotation (NPR), arising from polarizing fiber to chip grating couplers, by observing the limits of NPR in high cavity loss fiber lasers. We fabricated waveguides, transferred and patterned graphene to three different lengths, and observed different types of pulses based on the length of graphene, pump power and polarization state of the cavity. We confirmed the success of graphene processing through Raman scattering and saturable absorption measurements, as well graphene absorption simulation. High chip-coupling loss was overcome by using multiple erbium-doped fiber amplifiers. We believe this research will stimulate further interest in combining integrated photonics and fiber laser technologies, and the miniaturization of pulsed laser cavities. (C) 2018 The Japan Society of Applied Physics.