Directional Dependence of Acousto-Optic Figure of Merit
Directional Dependence of Acousto-Optic Figure of Merit
The acousto-optic figure of merit (FOM) indicates the ideal coupling orientation to maximize the refractive index change due to an acoustic signal.
The FOM is a function of the acoustic wave velocity, density, refractive index, and effective elasto-optic coefficient. All of these values (except the density) can be anisotropic. Three wave velocities may exist in any given direction: two transverse waves (primary oscillation perpendicular to the wave propagation direction) and one longitudinal wave (polarization in the same direction as the propagation). Select the type of wave (transverse or longitudinal) and one of four materials to plot. Certain directions have a very high FOM, indicating an ideal orientation for maximum interaction.