Caladan is focused upon the development of densely integrated optical transceivers for the data centers that underpin today’s internet. The Covid crisis has underlined how critical the internet is to our society, and has led to large increases in the bandwidth and capacities that need to be handled by today’s data center infrastructure. The recent emergence of AI applications is driving an enormous demand for computational resources, doubling every 3 to 4 months (!). In turn this is creating a strong demand for Terabit capable optical transceivers.
The backbone of these AI and cloud-based applications are data centers which consist of servers arranged into racks and interconnected using a hierarchical network. As the capacity and density of servers continues to grow, the links between them need to handle increasing capacity as well. In the past reporting period, we’ve witnessed emergence of the first 800G and even 1.6T optical transceivers. Interestingly, it is expected that the optical pluggables which were earlier predicted to be taken over by co-packaged optics, will last longer than originally thought, with 3.2T modules already being considered. This has to do with the difficulties in terms of supply chains and challenging specifications for co-packaged optics. Today, despite the use of complex Photonic Integrated Circuits (PICs) which allow integrating a large number of optical components such as modulators, photodetectors, possibly lasers and multiplexing functions into a chip, the fabrication of an optical transceiver still requires a large amount of sequential fabrication steps. Indeed photonics, high-speed electronics, fiber attachment parts such as fiber blocks need to be assembled piece-by-piece, even involving operator assisted active alignment. Testing also needs to be done piece-by-piece, which is costly at high volumes. It is important to note that even with a move to 300mm wafer manufacturing lines for Silicon Photonics, the increased amount of chips that can be extracted from a single 300mm wafer will require a linear increase in the amount of flip-chip, wirebonding, fiber attachment and other assembly equipment to maintain throughput.
The main objective of CALADAN is to break these bottlenecks. CALADAN will demonstrate automated, wafer-level integration of photonics and electronics into Terabit/s capable optical engines using micro transfer printing on 300mm Silicon Photonic engines, and connect these optical engines with fiber arrays using an industrially scalable vision-based automatic fiber attachment process. In this way, CALADAN will remove throughput bottlenecks in assembly lines and will be able to manufacture optical transceivers at 50% less cost compared to conventional solutions, achieving <0.1€/Gb/s for throughputs above 1million transceivers per year. The objectives are:
1) Demonstration of an automated wafer-level heterogeneous micro assembly process to integrate SiGe BiCMOS 56Gbaud integrated circuits onto Silicon Photonic transceivers manufactured in a 300mm wafer fabrication line.
2) Demonstration of an automated wafer-level heterogeneous micro assembly process to integrate uncooled quantum dot GaAs O-band lasers onto Silicon Photonic transceivers realized in a 300mm wafer fabrication line, capable of delivering +13dBm up to 85C
3) Demonstration of an automated vision based fast fiber attachment process using “through substrate” Silicon Photonic grating couplers with total assembly time less than 120 seconds per optical engine.
4) Demonstration of Terabit/s (multichannel 56Gbaud PAM-4 and 56Gbaud 16-ADPSK) optical transceivers using the micro transfer printing enabled manufacturing and fast fiber attachment processes.
5) Definition of wafer-level test procedures and testability for the manufacturing flow.
6) Establishment of a supply chain for Datacom Terabit/s transceivers manufactured using the CALADAN approach at 50% less cost compared to existing solutions for inter-rack and intra-rack applications, reaching 0.1€/Gb/s for volumes of at least 1million units per annum.
