Optical Fiber Vibration and Acceleration Model

We derive expressions for the group velocities of transverse electric and transverse magnetic electromagnetic waves in a stretched single-mode fiber. Stretching can occur either as a result of temperature changes of the spool on which the fiber is wound, or as a result of axial vibrations that accelerate and hence deform the spool. Long single-mode fibers are typically used in optoelectronic oscillators, where the group velocity plays a central role in determining the oscillator frequencies. The present idealized calculation assumes there is a fractional length change deltal/l, that results in stress in the fiber. This stress changes the optical properties of the fiber, and hence the group velocities, through its stress-optic coefficients. The principal result of the present calculation is that for optoelectronic oscillators, the main effect on the frequencies comes from the change of length itself rather than from the change in group velocities.