4-WAVE-MIXING PROCESSES IN TRANSLATIONAL OPTOMECHANICAL MEDIA

We study the mechanical, dielectric, and nonlinear-optical response of translational optomechanical media to incident electromagnetic radiation. These media consist of three-dimensional arrays of electrically small, isotropic particles that are mechanically supported but free to roll on stacks of very thin transparent planes. Electrostrictive forces tend to move the spheres in such a way as to form spatial variations in the particle density that correspond to electromagnetically induced spatial modulations in the array's dielectric constant. These modulations constitute translational optical index gratings that can be used to control the propagation characteristics of electromagnetic radiation. We study optical phase conjugation, pump-beam modulation, and harmonic phase conjugation at submillimeter, millimeter, and microwave wavelengths in this class of nonlinear media. We also examine the dynamics of these media from the perspective of the Langevin equations and determine the influence of thermal fluctuations on the properties of such an array.