AlliedSignal scientists have developed new polymeric materials for ultra-low-loss optical interconnection, particularly for the key wavelengths of 0.83, 1.3, and 1.55 microns. Developments of these materials has required a thorough understanding of fundamental principles of optical absorption due to both vibrational and electronic resonant absorptions. We have thus created materials with measure losses at 830 nm which are in the range of 0.02 dB/cm/ At longer wavelengths, the losses can be higher due to the vibrational absorption within the polymer. However through careful selection of chemical structure, polymeric materials with intrinsic loss below 0.08 dB/cm have been demonstrated at 1.55 micron wavelength. For wavelengths longer than 830 nm, single-mode and multimode waveguides with losses equal to the intrinsic loses have been fabricated.