Design for shaping, splitting, and diffusing light: a comparison

Abstract

Although over the past few years state-of-the-art point-to-point optical interconnects have shown the potential to fulfill the ever increasing demand for higher data communication bandwidth, still electronic interconnects are favoured over optical interconnects because electronics is a much more mature and established technology. However, when photonic interconnects could allow more complex and richer sets of interconnect patterns, by e.g. allowing for one-to-many optical interconnects (signal broadcasting) and reconfigurable point-to-point optical interconnects, they might outperform electronics both in terms of bandwidth and ease of reconfiguration. In this paper we do a concept study of several approaches to bring signal broadcast within an existing free-space (FS) plastic micro-optical interconnect intra-chip component. The original component consists of a combination of a refractive microlens array and a classical high-quality microprism. The idea of signal broadcasting can be realized by incorporating a fan-out diffractive optical element (DOE) at certain positions in this component. In a first design we integrate the DOE on the deflection edge of the microprism. For a second design we focus on the replacement of the refractive microlens array by their diffractive counterparts. In this approach the fan-out functionality of the DOE is combined with the lens functionality of the diffractive microlens arrays. In a third approach we target multi-faceted diffractive microlens arrays to implement the fan-out functionality. All presented designs can bring signal broadcast to the intra-chip optical interconnect level, although some of them will turn out to be more attractive for practical implementation in demonstrators. We compare and discuss the advantages and disadvantages of the proposed designs.