Alignment and fabrication tolerances of planar gratings for board-to-board optical interconnects

The use of diffraction gratings to trap optical beams in substrates for optical interconnect applications has been proposed by many. We analyze the alignment and fabrication tolerances of such gratings to make them viable for such applications. The use of chirped circular gratings is proposed as a means of compensating for transverse-optical beam misalignments. Fabrication of 1-, 2-, and 4-microm-period gratings on glass substrates through ion-beam milling and their analysis are presented. High diffracted orders were confined to the substrates through total internal reflection.