The approach of one embodiment of the present invention is to mechanically vibrate a length of fiber optic cable transmitting coherent laser light, so that a mechanical resonance in the optical fiber is excited. This is achieved by suspending the fiber optic cable between two points and controlling both the axial tension on the suspended fiber optic cable as well as the mechanical forcing frequency. The cyclic, high-frequency mechanical perturbations of the fiber rapidly vary the path length and internal reflection angles of one or more respective modes of the transmitted laser light. In certain embodiments, the system may be tuned to induce a standing mechanical wave in the fiber. Higher-harmonic waveforms and higher amplitudes in the resonant fiber produce excellent speckle reduction and uniform intensity distributions.