Marshall C. Hudson

Calculation of the Maximum Optical Coupling Efficiency into Multimode Optical Waveguides

The application of Liouvilles theorem from statistical mechanics to a distribution of rays emanating from a light source provides a method of visualizing and calculating the maximum efficiency achievable when couping the radiation to a receiver. It is shown that the maximum coupling efficiency depends only on measurable spatial and angular boundary conditions of the source and receiver together with knowledge of the source radiance distribution. Knowledge of the maximum coupling efficiency permits evaluation of any optical system which might be used to effect coupling. A specific example is given for coupling radiation from a light emitting diode to a cylindrical, multimode, optical waveguide.

The Star Coupler: A Unique Interconnection Component for Multimode Optical Waveguide Communications Systems

The use of optical waveguides in communications systems may require the interconnection of many interactive terminals. The preferred configuration for passive interconnection in optical waveguide systems is shown to be a configuration termed the Star system. The central interconnecting component, the Star coupler, is described, and the performance of a system incorporating it is compared to that of an equivalent system using a common optical bus and Tee couplers. The Star system is shown to have lower terminal-to-terminal loss, easier upgradability, enhanced reliability and survivability, inherent bidirectionality, and inherent equivalence of all terminals. Construction of two Star couplers is described, and measurements of their performance characteristics are reported.