Provided are a reflective semiconductor optical amplifier (R-SOA) and a superluminescent diode (SLD). The R-SOA includes: a substrate; an optical waveguide including a lower clad layer, an active layer independent of the polarization of light, and an upper clad layer sequentially stacked on the substrate, the optical waveguide comprising linear, curved, and tapered waveguide areas; and a current blocking layer formed around the optical waveguide to block a flow of current out of the active layer, wherein the linear and curved waveguide areas have a single buried hetero (BH) structure, and the tapered waveguide area has a dual BH structure.