Embodiments relate to a polymer waveguide including a substrate, a cladding layer made of a first polymer, formed on the substrate, wherein a first monomer is polymerized into the first polymer, and the cladding layer has a groove for the waveguide by removing part of the cladding layer, and a core accommodating graphene therein, formed on the groove, a method for manufacturing the same, and a passively mode-locked laser based on the polymer waveguide.