FREE-VIBRATIONS OF A FUSED BICONICAL TAPER LIGHTWAVE COUPLER

A simple formula is obtained for the assessment of the fundamental frequency of lateral vibrations of a fused biconical taper (FBT) lightwave coupler, subjected to initial tensile strain (force). The obtained formula considers the nonprismaticity of the coupler, as well as the nonlinear stress-strain relationship of the material, and can be used to determine the initial strain resulting in a sufficiently high fundamental frequency. This formula can be applied also for the evaluation of the initial tensile force, stress and strain from the measured vibration frequency.