Elastic waves in rods and optical fibers

This talk reviews elastic waves in rods, with mention of their possible importance in optical fibers. The formal solution of the boundary value problem of the three‐dimensional theory of elasticity for waves in rods was given over a century ago by Pochhammer and Chree. It was only about 50 years ago that important computations were done that enabled calculated results to be compared with experimental data for longitudinal waves [D. Bancroft, Phys. Rev. 59, 588–593 (1941)] and flexural waves [G. E. Hudson, Phys. Rev. 63, 46–51 (1943)]. The modulation or scattering of light by acoustic waves in optical fibers can be either harmful as in catastrophic stimulated backward Brillouin scattering [E. P. Ippen and R. H. Stolen, Appl. Phys. Lett. 21, 539–541 (1972)] or it can be put to practical use as has been attempted in devices such as acoustically mode‐locked fiber lasers [Phillips et al., Opt. Lett. 14, 680–682 (1989)].