Provided is a super luminescent diode having low power consumption due to low threshold current and a high output power in low-current operation, which is suitable for an external cavity laser. The super luminescent diode for use in the external cavity laser is divided into a super luminescent diode (SLD) region and a semiconductor optical amplifier (SOA) region to provide a light source having a low threshold current and a nearly double output power of a conventional SLD.A super luminescent diode-integrated reflective optical amplifier includes a substrate that has a super luminescent diode (SLD) region and a semiconductor optical amplifier (SOA) region for amplifying light generated from the SLD region, an optical waveguide that has a buried heterostructure, the buried heterostructure including an active layer extending over the SLD and SOA regions on the substrate and tapered in the SOA region; a current blocking layer formed around the active layer for blocking a current flow to layers other than the active layer, the current blocking layer including a stack of semiconductor layers having different conductivity types; and a clad layer formed on the optical waveguide and the current blocking layer.