Abstract: An optical coupler device is provided with gradient index first and second lenses, with each lens having an outer endface with one or more ports at a predetermined location defined by a waveguide such as an optical fiber. A narrow bandpass optical filter is disposed between inner endfaces of the first and second lenses. In one embodiment, the second lens is in coaxial mechanical alignment with the first lens so as to have a common optical axis. An input waveguide and an optional reflection waveguide are disposed on the outer endface of the first lens on opposite sides of the optical axis. A transmission waveguide is disposed on one side of the outer endface of the second lens and is positioned at a non-zero angle with respect to the optical axis in order to compensate for a previously unrecognized lateral beam displacement caused by the optical filter.