Patent ID: 7460302
Filing Date: 2008-12-02
Classification: G02B,G02F,H04J

Abstract:
1. An optical device comprising: a light transmissive substrate having at least two major surfaces, a first surface and a second surface, and edges; a first and a second grating, each having an X-axis and a Y-axis, located on at least one of said substrate surfaces, at a constant distance from each other; each grating having a lateral dimension including at least one sequence of a plurality of parallel lines, wherein the spacing between said lines gradually increases in a direction away from an edge of the grating up to a maximum distance between said lines, and wherein the spacing between the parallel lines of the second grating increases in the same direction as the spacing of the first grating; the dimension of the second grating along the X-axis being smaller than the dimension of said first grating in the X-axis, while the dimensions of the gratings along the Y-axis are substantially the same; a light source coupling a light beam into said substrate by said first grating in a first direction, and the light beam being coupled out from the substrate in a second direction by said second grating; said second direction of the light beam being controlled by changing a refractive index of the substrate or by changing a wavelength of the light source; wherein the refractive index of said light-transmissive substrate between said gratings is dynamically, externally controlled.