Radiation Hard, High-Bandwidth Optical Fiber Links for Detectors at High Energy Colliders

While commercially available, highvolume, optical communication products can achieve high data rates e.g. 100 Gbps, they are designed to operate in controlled environments such as in server racks for datacenters, and are not intended for operation in extreme environments such as those found near the center of High Energy Physics HEP experiments, where radiation levels are projected to be an orderof magnitude higher than encountered today. The purpose of this research and development R&D SBIR program is to develop lowcost, highbandwidth optical fiber links for transmitting data signals out of extreme radiation environments, which has applications across multiple scientific and commercial interests. The overall objective of this SBIR program is to develop radiation hard, highbandwidth optical fiber links for detectors at high energy colliders, that interface with frontend application specific integrated circuits ASIC currently under development such as the RD53 readout integrated circuit ROIC. The optical fiber link will be based on an array of remoted silicon photonic SiPho based electrooptic modulators EOM, that use the output signals from the frontend ASIC to drive the modulators and provide a highcapacity readout link to the data analysis electronics in the benign environment i.e. the counting room. Only the array of remoted SiPho EOMs are subjected the highest radiation levels, while the remaining sensitive components of the link are placed in the counting room. In Phase I of this SBIR program, the team worked with DOE scientists to identify future HEP applications and establish performance metrics of the optical fiber link to be used in the identified applications. The team also analyzed the performance of electrooptic modulators formed in a commercial silicon photonic process, by measuring their electrical and optical performance and characterizing existing prototype devices up to a total ionizing dose TID of 8.6 Mrad. The measurements were used to establish a physicsbased model, in connection with commercially available software, and led to further insights in design methodologies of SiPho based EOMs that can meet the target of 100 Mrad TID. An alternative commercial SiPho process was identified and has shown a substantial increase in radiation performance through simulations. In Phase II of the SBIR program, the team proposes further investigation of the newly identified commercial SiPho process, through a combination of simulation, modeling, and characterization of new prototype devices. The team will work with DOE scientists to characterize the new devices via Xray and proton irradiation experiments, which will be fed into a highlevel link model to predict performance and properly design the entire optical link according the performance requirements identified in Phase I. The program will culminate in the demonstration of a singlechannel optical link, followed by a multichannel optical link demonstration and hardware deliverable, using the RD53 ROIC as the signal source, demonstrating a successful optical link architecture that is scalable and fulfills DOE requirements for future HEP experiments.