Optical beam spot size converter

An optical beam spot size convertor is provided having a body. The body comprises a first optical waveguide having a first refractive index and a plurality of second optical waveguides each having a second refractive index higher than the first refractive index. The first optical waveguide is arranged to receive an input optical beam. The first optical waveguide is further arranged such that light from the input optical beam is coupled from the first optical waveguide into the plurality of second optical waveguides. The body further comprises an output optical waveguide and a reflective part coupled to the plurality of second optical waveguides and to the output optical waveguide. The reflective part is arranged to focus optical beams received from the plurality of second optical waveguides into a single optical beam which is directed to the output optical waveguide.