Patent ID: 8107152

Claim:
An electrically tunable optical filter, comprising: a first filter element comprising: a first planar, singular solid crystal comprised of a material that exhibits birefringence and is electro-optically active and having a first and second surface and a first crystal thickness; a first substantially transparent electrode adjacent to said first surface and a second substantially transparent electrode adjacent to said second surface; a first polarizer located substantially proximate to said first surface and having a first axis of polarization oriented at 45 degrees to an optical axis of said crystal; and a second polarizer located substantially proximate to said second surface and having a second axis of polarization oriented at 45 degrees to said optical axis of said crystal and either parallel or perpendicular to said first axis of polarization; wherein the first crystal is comprised of lithium niobate; and wherein a crystalline structure of said first crystal is oriented such that when a voltage is applied parallel to the direction of light between said first and second electrodes, the retardation of said first crystal changes thereby altering the spectral transmission of said optical filter.