FIELD ANALYSIS OF 2-DIMENSIONAL FOCUSING GRATING COUPLERS

The method that we have developed [P-P. Borsboom, Ph.D. dissertation ( Delft University of Technology, Delft, The Netherlands); P-P. Borsboom and H. J. Frankena, J. Opt. Sec. Am. A 12, 1134-1141 (1995)] is succe ssfully applied to a two-dimensional focusing grating coupler. The fie ld in the focal region has been determined for symmetrical chirped gra tings consisting of as many as 124 corrugations. The intensity distrib ution in the focal region agrees well with the approximate predictions of geometrical optics. In the case of short focusing grating couplers high-frequency intensity variations are observed in the focal region.