Abstract: An optical device for use with an optical signal propagating therein comprising a first waveguide having a core which is terminated at an endface, in which either (a) the endface of the waveguide is uncontrolled (for instance not being smooth, not being optically flat, and/or not being at an angle optimised to avoid deleterious back-reflection) or (b) the first waveguide a polymer waveguide or (c) both. A second waveguide is terminated at an endface within about 50 &mgr;m of the endface of the first waveguide so that the waveguides are optically coupled. A pigtailing material is situated in the gap between the first waveguide and the second waveguide and has a refractive index within about 0.03 of the refractive index of the core of the first waveguide. When the first waveguide is a polymer waveguide, its core preferably has an effective refractive index either less than about 1.4 or greater than about 1.57 (at 1550 nm).