Indium phosphide (InP) for optical interconnects

We present InP as the incumbent technology for data center transceiver and switching optics. We review the most popular InP monolithic integration approaches in light of photonic integration being recognized as an increasingly important technology for data center optics. We present Multi-Guide Vertical Integration by OneChip Photonics as an example of a low-cost InP integration platform, showcased for 100GE transceiver optics, and we also review optical switching technology and present highly integrated InP optical switches developed at the COBRA Research Institute. We compare InP to the competing Si photonics technology, where we argue that Si photonics is a cost-competitive technology, but only for very large volumes, which are not yet representative of the data center market of today and in the near future. We conclude by pinpointing the future trends for the optics in data centers, including the increased level of optics/electronics integration, the increased use of spin-coated polymer devices, and novel heterogeneous integration by flip-chip bonding of separately fabricated InP and Si chips, as an alternative to the more challenging, full monolithic InP integratio