Method for fabricating ultra thin single-crystal metal oxide wave retarder plates and a waveguide polarization mode converter using the same

摘要

A method for fabricating ultra-thin single-crystal metal oxide wave retarder plates, such as a zeroth-order X-cut single-crystal LiNbO3 half-wave plate, comprises ion implanting a bulk birefringent metal oxide crystal at normal incidence through a planar major surface thereof to form a damage layer at a predetermined distance d below the planar major surface, and detaching a single-crystal wave retarder plate from the bulk crystal by either chemically etching away the damage layer or by subjecting the bulk crystal having the damage layer to a rapid temperature increase to effect thermally induced snap-off detachment of the wave retarder plate. The detached wave retarder plate has a predetermined thickness d dependent on the ion implantation energy. A half-wave plate fabricated in accordance with this method may be used in conjunction with an optical waveguide section to form a TE-TM polarization mode converter by mounting the half-wave plate in a groove in the waveguide section perpendicular to the direction of wave propagation therein, bonding the half-wave plate to the back-end facet of the waveguide section or bonding the half-wave plate to the front-end facet of the waveguide section. In each case the normal mode axes of the half-wave plate is at 45 DEG with respect to the direction of the electric field vector of the TE or TM mode of propagation in the waveguide section.