Polymer based optical interconnect components for high-speed Datacom approaches – Micromachining supported manufacturing

Abstract

Abstract Optical data communication will play an important role in future high speed data links. Especially in Datacom applications data rates in Gbps area will be desired. An overall low cost approach is needed on both sides, for the opto-electronic integration and for the passive optical interconnects. Opto-electronic integration will be reached through the use of one- or bidirectional transceivers for Datacom based – in future – on surface emitting lasers (VCSEL), instead of LEDs used today, and economically favorable silicon detectors. This additionally requires passive optical interconnects using beam shaped low-cost micro-optical components such as, microlenses for in- and out-coupling which are more and more popular in recently developed opto-electronic devices. Ideally, micro-optical components can be integrated in passive optical interconnects and replicated in polymer materials for the cost reducing. Hence, the increase of data rate depends on the quality of the optical surfaces. In this paper the micromechanical manufacturing technologies of microcomponents with optical surfaces are discussed. Furthermore, polymer based components are presented which can be used for coupling and routing of optical signals, e.g. a passive optical interconnect for the passive coupling into photodiode or from VCSEL and optical N × M star couplers. The polymer based interconnect module has been realized in different polymers (polymethyl methacrylate, PMMA, and cycloolefin copolymer, COC). Total loses and data rates achieved are 3.3 dB and 2 Gbps, respectively. Average total loss an e.g., polymer based 16 × 16 optical star coupler is better than 17 dB per channel with a uniformity of 3 dB. For replication of polymer substrates of these components hot embossing tools have been produced by combination of deep lithography, ultra-precise milling and micro-machining.