A waveguide's a structure which guides waves, such as electromagnetic waves or sound waves. There're different types of waveguide for each type of wave. Waveguides differ in their geometry which can confine light in one dimension such as in slab waveguides or two dimensions as in fiber or channel waveguides. Electromagnetic waveguides Waveguides can be constructed to carry waves over a wide portion of the electromagnetic spectrum, but are especially useful in the microwave and optical frequenc… (More on Waveguide)