This chapter provides an overview of guided-wave acousto-optical devices. It provides the brief introduction of surface acoustic waves (SAW). These types of acoustical waves are used for most of the integrated acousto-optical devices. The chapter provides a short review on Bragg-type acousto-optical devices in planar waveguides and some of their applications. It focuses on acousto-optical devices based on collinear polarization conversion and some of their applications in wavelength division multiplexing systems. SAWs are used for integrated acoustooptical devices. These SAWs are special types of acoustical waves that are bounded close to the surface of the crystal. Most of the acousto-optical devices take advantage of integrated acoustical waveguides to confine the SAWs into localized regions, yielding large acoustical power densities even at low or moderate overall acoustic power levels. Polarization splitters are applied to separate the transverse electric and transverse magnetic components of an incoming wave and route them to different optical waveguides.