Design, Fabrication and Testing of Assembly Features for Enabling Sub-micron Accurate Passive Alignment of Photonic Chips on a Silicon Optical Bench

Abstract : In this paper, we report on passive alignment with sub-micron precision of two photonic chips on a silicon optical bench. An effective design principle to minimize the tolerance chain is presented and applied to a case study. The chips have been successfully manufactured and individual characterization of the chips revealed that all critical dimensions were within or close to specs. Sub-pixel analysis of images of assembled chips showed that a repeatability of 0.3 μm from a single photonic chip to the silicon optical bench can be achieved. Moreover, it was demonstrated that passive alignment features defined in the waveguiding layers are robust enough to function as mechanical endstops.