Spectral response of low-loss optical waveguides

The attainment of 20-dB/km attenuation in experimental single-mode glass optical waveguides has spurred interest in their use for optical communications. The primary wavelength region of interest is in the red or near-infrared region of the spectrum. In this work independent attenuation measurements from 600 nm to 1060 nm have been made on low-loss waveguides and bulk cladding glass, using both laser and scanning-prism monochromator sources. Three bands were observed in the waveguides, at 725 nm, 875 nm, and 950 nm, and identified as due to OH in the glass. Absorptions too small to be precisely measured in the bulk glass measured in them. are seen to be exceedingly important in the waveguides and easily measured in them.