Optical waveguide positioning feature in a multiple waveguides connector

A coupling unit, comprising:

• a light coupling element comprising an attachment area for receiving and permanently attaching to a plurality of optical waveguides;
• one or more grooves provided at the attachment area, each groove configured to receive an optical waveguide having a width;
• each groove having a first region and a bottom surface, the first region in cross section having substantially parallel sidewalls separated by a spacing;
• and
• each groove having a longitudinal transition section comprising a first end and a second end, the first end having a sidewall spacing greater than the width of the optical waveguide, and the second end having a sidewall spacing less than the width of the optical waveguide.