Two mirrors guiding light experience attractive or repulsive forces according to the eigenmode type of symmetry,
but regardless of the specific details of the guiding structure. A transverse evanescent mode (TM or TE) that
has an anti-symmetric transverse field causes repulsion, while attraction occurs when the mode has a symmetric
transverse field. Transverse propagating modes, however, are always repulsive. One possible application for this
phenomenon is to use a symmetric mode supported, for instance, by two properly designed Bragg mirrors. By
varying the wavelength of the mode injected into the waveguide, it is possible to cross the light-line and switch
between attraction and repulsion. If the mirror is free to move in the transverse direction, then this is a scheme
for controlling its motion. Another possibility is to create a stable equilibrium with a superposition of transverse
evanescent symmetric and anti-symmetric modes. For this purpose, a more appealing configuration than Bragg
mirrors is a waveguide that consists of two dielectric slabs where the light is guided by total internal reflection.
Each slab is trapped in a potential well resulting in optical binding by eigenmodes.