Abstract
An apparatus for polarization independent acousto-optical tunable filtering and a method for the same diffracts the input light into a first output light free of acoustic effect and a second output light affected by acoustic effect. A polarization beam displacer separates the input light into two lights orthogonal to each other. Plural polarization rotators rotate polarization angle of the light by 90 degree. An AO device rotates the polarization angle of the light of a specific wavelength by 90 degree. Finally, a suitably designed beam combiner combines two orthogonal lights. The filtering operation is independent of polarization, and has the advantage of high extinction ratio, smaller size, and low cost.