Light Transmission in a Multiple Dielectric (Gaseous and Solid) Guide

Hollow metallic and dielectric waveguides for long distance optical transmission were suggested by the author and R. A. Schmeltzer.1 An alternative, proposed by S. E. Miller, is the coaxial structure shown in Fig. 1. The internal medium r ^ a, as well as the external one, r ^ b, are gases of refractive indexes n and n3 such that ni > n3 . Both gases are kept apart by a dielectric tube of thickness c = b -- a and refractive index ?ii . Since n and m2 are both bigger than n 3 , the structure will guide modes similarly to a dielectric waveguide, but it is of interest to find out if there are modes with most of their power traveling within the internal gas and not in the dielectric tube. If these modes exist, they 97 98 T H E B E L L S Y S T E M TECHNICAL J O U R N A L , J A N U A R Y 1 9 ( 3 0 / 1 / I 1 y V A i i 2a i I 2b 1 F i g . 1 -- M u l t i p l e dielectric guide. (?i 3 -- iu)/(ns -- « i ) 5C 1.