An optic switch for cross-connecting input light signals incoming from inlet fiber cables to outlet fiber cables is disclosed that makes use of a holographic filter (5) having a series of preformed different speckle patterns, each in the form of a hologram (H₁, H₂, . . . ). Associated with input light signals guided past respective inlet passages (4in) of a multimode waveguide (4), different speckle patterns are formed by applying different control voltages across respective electrode pairs (10, 10a) provided thereon. These speckle patterns past a single outlet passage (4out) of the multimode waveguide (4) into which the inlet passages (4in) converge are joined together and enter the holographic filter (5) in which an input light signal is selectively switched, addressed and cross-connected to an outlet waveguide (2) through a region thereof where a formed speckle pattern coincides with a preformed speckle pattern. The multi mode waveguides (4) is formed in, e.g., a LiNbO₃ photorefractive substrate (3).