Single mode integrated-optical wide-band channel waveguides (SOWCWs) have been defined as a novel type of channel waveguides. The wavelength ranges (bandwidths) of both single mode operation in the channel waveguide and efficient junction-splitting using the same channel waveguides, that is for constant combining or splitting of light in integrated-optical devices like Y junctions, can easily comprise the entire visible wavelength region. In this case, the SOWCW is a real single mode white light channel waveguide. The optical bandwidths of both Rb↔K ion-exchanged channel waveguides in KTiOPO4 (KTP) as an example of SOWCWs and Rb:KTP Y junctions in comparison with those of conventional titanium-indiffused channel waveguides and Y junctions in LiNbO3 have been theoretically calculated and experimentally verified. The channel waveguide attenuation, the coupling efficiency to single mode fibers, and the splitting ratio of Y junctions, especially, show no significant wavelength dependence in the Rb:KTP case. Use of SOWCWs could open up new directions of integrated optics. As an example, the basic three-color-mixing device is chosen from a variety of possible applications in the field of integrated-optical color image generation.