Tutorial 2
From Co-Packaged Optics to Co-Packaged Photonic Systems

Mohamed Elkabbash , University of Arizona

The continuing growth of bandwidth in switches, processors, and computing accelerators is making the power and signal-integrity costs of long electrical interfaces increasingly difficult to sustain. Co-packaged optics addresses this electrical I/O bottleneck by placing photonic optical engines within the same package as the electronic ASIC, thereby reducing electrical reach and enabling high-bandwidth optical connectivity. This tutorial examines co-packaged optics primarily from the perspective of the integrated photonic technologies required to realize and scale these systems.

We will first introduce the architecture of a co-packaged optical engine and its principal components, including waveguides, splitters, wavelength filters, modulators, photodetectors, light sources, and optical couplers. Particular attention will be given to two closely related challenges: operation in the high-temperature environment surrounding advanced electronic ASICs and the scalable delivery of optical power and signals into and out of the package. We will compare on-chip, heterogeneously integrated, and external light-source architectures; active thermal stabilization and athermal photonic designs; and fiber-coupling approaches including edge and grating couplers, elephant couplers, three-dimensional reflectors, freeform couplers, and package-level optical waveguides. Finally, we will examine bandwidth-density scaling through wavelength- and mode-division multiplexing, multicore fibers, multilayer routing, and three-dimensional photonic integration. The tutorial will conclude by considering how the technologies developed for optical I/O could enable a broader class of co-packaged photonic systems for sensing, LiDAR, computing, memory, and hardware security.

Dr. Mohamed Elkabbash is an Assistant Professor at the Wyant College of Optical Sciences and Physics Department, University of Arizona. He leads the Quantum Photonics and Nanophotonics Group (QPANG). He works on the areas of nanophotonics and metamaterials, co-packaged optics, quantum photonics, and ultrafast light-matter interaction. His current research interests are copackaged optics, the integration of nanophotonics with CMOS foundry processes, developing high-speed spatial light modulators, developing extreme UV nanophotonic devices, photonic computing, photonics-based sustainable cooling, and tabletop optical tests for fundamental physics. He has published more than 70 publications, a book, and 2 patents with more than 30 patents pending.