1. An optical printed circuit board, comprising:an electrical conductor arranged for conducting electric signal;
an optical waveguide arranged for transmitting optical signal; and
an optical waveguide coupling interface arranged at an end of the optical waveguide, the optical waveguide coupling interface being arranged for engagement with an external optical device to optically couple the external optical device with the optical waveguide;
wherein the optical waveguide coupling interface comprises an engagement mechanism with:a socket defining a space for receiving with a corresponding plug on the external optical device, the space extending in parallel with a corresponding end portion of the optical waveguide; or
a plug arranged to be received in a corresponding socket on the external optical device, the plug extending in parallel with a corresponding end portion of the optical waveguide.