An optical integrated circuit comprises optical waveguides, grooves formed by etching the upper cladding layer, the core layer and all or parts of the lower cladding layer close to a end section of the optical waveguide to intercept light transmitted through the core layer of the optical waveguide or to couple light into the core layer, a plurality of bonding pads formed around the groove, micro-mirrors and active optical elements. Such a PLC based optical integrated circuit and a method of manufacturing the same provides a low-cost manufacturing of optical integrated circuits and high quality mirrors for vertical optical coupling scheme.