High diffracted power and bandwidth in acousto‐optic guided wave Bragg cell are critically dependent on the interaction efficiency between the surface optic and acoustic waves. Through the overlapping integral, diffraction efficiency depends dramatically on the acoustic and optic field shapes in the crystal, and the surface acoustic wave penetration depth is strongly dependent on the frequency; thus, either the interaction efficiency and the acousto‐optic bandwidth are strictly related to the guide geometry. For these reasons the technological process to build an optical slab guide plays a critical role in fulfilling the desired characteristics of the Bragg cell; it determines the optical field shape in the crystal and, thus, the overall limitation of the cell. In the present work, a method to analyze the technological process role for the lithium niobate Ti diffused guide is presented for a collinear guided wave Bragg cell.