Molecular design of processable nonlinear optical (NLO) polymers is discussed for applications to devices such as ultrafast optical switches. Channel waveguides must be fabricated in order to develop polymeric NLO switching devices that can be driven with lower laser power. For these purposes, we propose molecular structures that reduce attenuation loss and allow the development of highly processable NLO polymers. Third-order nonlinear optical properties, χ(3), of the novel NLO polymers are around 10−10 esu in the 1.5 μm wavelength region. Even in off-resonant regions, the χ(3) values are around 5 × 10−11 esu. Single Mode channel waveguides of the polymers are fabricated using a standard photo-process. Attenuation loss through a film and also for a single mode waveguide at 1.32 μm wavelength is Measured. Nonlinear optical properties of novel, processable, heteroaromatic polymers with large χ(3) are also discussed. Several types of heteroaromatic polymers are developed with a structure in which π-electron excessive heteroaromatic compounds and π-electron deficient heteroaromatic compounds are combined to induce strong nonlinearity. The charge transfer between heteroaromatic rings on the π-conjugated sequences is thought to influence the properties of certain excited states that enhance χ(3) These polymers have excellent potential for use in fabrication of optical switching devices.