Abstract: A waveguide turn having two waveguides oriented at an angle with respect to one another and optically coupled to one another by a reflective surface. In one embodiment, the reflective surface is a side of a trench formed in the core and cladding regions of the waveguides, which is designed to reflect light based on total internal reflection (TIR). The reflective surface can be designed to have an appropriate curved shape to reduce coupling losses between the waveguides. Due to relatively sharp turn (reflection) angles accessible with the reflective surface, the circuit area occupied by a waveguide turn of the invention is significantly smaller than that for a typical prior-art waveguide turn.