Abstract

The time-dependent heat equation is solved in a cylindrical geometry of finite length with heat loss by radiation and conduction. Exact expressions are derived for the time constants of radial and longitudinal modes. The steady-state solution is obtained in longitudinal modes and used as the initial state for the decay. A simple expression is presented for the ratio of the amplitude of the first-order longitudinal order mode A₁ and the corresponding time constant τ₁ fit with the separate expressions for A₁ and τ₁. These parameters are experimentally readily accessible and directly yield the absorption coefficient α of rod-shaped compound glass from which optical fibers are to be drawn.

© 1979 Optical Society of America

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