Description
Acousto-Optic devices are used in laser equipment
for electronic control of the intensity and position
of the laser beam. In this note, we will explain the
theory and application of acousto-optic
modulators. Acousto-optic interaction occurs in all
optical mediums when an acoustic wave and a
laser beam are present in the medium. When an
acoustic wave is launched into the optical medium,
it generates a refractive index wave that behaves
like a sinusoidal grating. An incident laser beam
passing through this granting will diffract the laser
beam into several orders. With appropriate design,
the first order beam has the highest efficiency. Its
angular position is linearly proportional to the
acoustic frequency, so that the higher the
frequency, the larger the diffracted angle.
