Embodiments of the present disclosure provide a laser diode. The laser diode includes: a semiconductor substrate, a waveguide layer and a light wave limiting layer. The waveguide layer is disposed on the semiconductor substrate, and comprises a quantum well layer. The light wave limiting layer is disposed on a surface of the waveguide layer, and is configured to limit a light wave to be transmitted in the waveguide layer. The quantum well layer includes a plurality of quantum well regions that are disposed along a transmission direction of the light wave, and the quantum well regions respectively have gain peaks of different wavelengths. The embodiments of the present disclosure further provide a manufacturing method of a laser diode and a passive optical network system using the laser diode.