Measurements show that single-mode waveguides can be constructed which have radiation losses of about 7 dB/km—very close to the intrinsic material scattering loss. These waveguides, with total losses between 60 and 70 dB/km, have permitted the measurement of bending losses which become dominant at radii of curvature of a few centimeters. An approximate theory based on bending a rectangular guide appears to represent the circular waveguide results very well.
Associated with a signal transmitted down a waveguide are multiple back and forth scatterings. These produce a delayed decaying interference trailing a sharp signal pulse. An analytical description of this phenomenon enables an estimate of its effect on an optical waveguide's information-carrying capacity. For the example of a signal-to-interference ratio of 100 in a 1-km fiber of 20-dB attenuation, a bit rate limitation occurs when the fractional backscattered power captured per unit length exceeds 1.3 dB/km.
Waveguide propagation of a pulse-modulated carrier wave is formulated to include distortion due to dispersion in both attentuation and phase velocity. An optimum input gaussian pulse width exists for maximum information carrying capacity. Results are applied to a numerical study of several singlemode glass optical waveguides in which mode and dielectric dispersion may total zero at some wavelength. For our low-loss (20 dB/km) guides in kilometer lengths, information rates of at least 3 x 10(10) bits/sec should be attainable.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.