Multi-channel optical intra-chip interconnections based on free-space modules: towards manufacturable solutions. Michael Vervaeke a , Christof Debaes a , Heidi Ottevaere a , Patrik Tuteleers a Wim Meeus b , Marnik Brunfaut b , Jan Van Campenhout b , Hugo Thienpont a a Vrije Universiteit Brussel (VUB), Dep. of Applied Physics and Photonics (TONA/TW), Pleinlaan 2, B-1050 Brussels b Universiteit Gent (RUG), Dep. of Electronics and Information Systems (ELIS), Sint Pietersnieuwstraat 41, B-9000 Gent We report on the use of a free-space optical module to establish multi-channel intra- chip optical interconnections on an opto-electronic field programmable gate-array (OE-FPGA). The optical component was prototyped and replicated in our labs to provide 2x8 parallel channels. After careful alignment of the free-space module on the OE-FPGA 4 channels were interconnected with sufficient data quality to ensure at least 10 Mb/s per channel. We present our latest results with a new optical interconnection module, composed of a glass prism and in-house made lenslet arrays capable of interconnecting up to 330 channels. Introduction Moore’s law still dictates the evolution of the transistor count in digital IC’s. However, the downscaling of the interconnect feature size deteriorates the signal quality and worsens the design complexity of the link. Advanced detection techniques should be used in order to circumvent this interconnect aspect ratio limit, imposed merely by the dimensions of the link wiring 1 . After the introduction of optics as a “wire replacing technology” 2 , a lot of effort has been put in determining the potentialities 3 of optical interconnects. The trend for the introduction of optical interconnects in the lower levels of the interconnect hierarchy has been set, possibly reaching the on-chip interconnection level. The latter approach is the subject for many frenzy discussions and the outcome is as yet unclear. Despite the ongoing debate, we fabricated and replicated a free-space micro-optical interconnection module (OIM) and used it to establish for the first time to our knowledge a working multi-channel interconnect within a chip. The module interconnects photonic I/O’s on an OE-FPGA, fabricated within the EC project “Optically Interconnected Integrated Circuits” 4 . In this paper we discuss the link experiments with this intra-chip optical interconnect as well as our efforts to build a 3D optical block with a higher channel count and density using a mechanically aligned glass prism. The micro-optical pathway block The micro-OIM we propose uses micro-optical beamshaping and beamdelivering structures 5 , as shown in Figure 1, to interconnect emitters and detectors on the same chip via free space. A microlens array collects and collimates the light coming from a flip-chip bonded multimode VCSEL array. As the light travels through the structure, it encounters a microprism which reflects the light back to the substrate. A second microlens focuses the light onto the detector surface. The OIM containing the necessary