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

1966; Institute of Electrical and Electronics Engineers; Volume: 45; Issue: 1 Linguagem: Inglês

10.1002/j.1538-7305.1966.tb04206.x

2376-7154

E. A. J. Marcatili,

Spectroscopy and Laser Applications

A low-loss transmission medium for optical frequencies consisting of a thin-wall dielectric tube that separates an internal high-density gas from an external low-density gas is proposed. Approximate transmission characteristics of the coaxial structure are derived via the analysis of a two-dimensional model. The multiple dielectric guide behaves similarly to a dielectric waveguide, and the fundamental mode attenuation due to losses in the solid tube is calculated to be small even at the worst possible choice of the tube wall thickness. Assuming (i) an internal diameter of 5×10 −4 m, (ii) wall thickness of 10 −5 m, (iii) loss in the solid dielectric of 1 neper/m, and (iv) internal and external gases, CO 2 and air, respectively, both at 20 atmospheres, the theoretical attenuation for the fundamental mode is of the order of 0.05 db/km and the attenuation of each mode is roughly four times smaller than that of the next higher one.