advancing a dicing blade across said plurality of light waveguides while lowering said dicing blade to a predetermined first level of an initial depth at least at a plurality of points where said light waveguides meet so as to make a preliminary cut in each of said light waveguides to form a preliminary groove having an initial depth,

releasing said dicing blade away from said light waveguides,

measuring an open-end width of the preliminary groove at each of said points to (1) calculate the initial depth of said preliminary groove based upon said open-end width and a geometrical configuration of the dicing blade, and (2) calculate a target level for each of said points in terms of said predetermined first level, said initial depth of the preliminary groove, and a final depth of a groove, said target level being defined as a distance from said first level minus a difference between the initial depth of said preliminary groove and said final depth of said groove; and

advancing said dicing blade along a straight path across said plurality of light waveguides while lowering said dicing blade to said target level at each of said points to cut said groove having said final depth and a slanted surface to define said deflection mirrors,

wherein the initial depth of the preliminary groove is less than the final depth of the groove,

wherein said plurality of light waveguides are arranged in a horizontal plane and spaced in a parallel relation with each other,

wherein said dicing blade has a cutting end with a flat top cutting face and at least one slanted side cutting face,

wherein said final depth is not greater than a width of said flat top cutting face, and

wherein said slanted surface of said groove is formed by said slanted side cutting face of said dicing blade.