Optical computers have often been seen as the next step in the future of computing ever since the 1960s[1]. They promise much higher energy efficiencies, while offering near latency free, high-performance computing (HPC), as well as easily scalable data bandwidth and parallelism. Ever since 1957 with von Neumann publishing the first related patent[2] and Bell Labs creating the first optical digital computing circuits[3, 4, 5, 6], the field has gone through multiple hype cycles and downturns[1]. While an all-optical, general-purpose computer hadn’t been achieved yet so far, the DOC-II[7] did come close, still requiring an electronic processing step each iteration. A lot of results from the research since has found its way into use on the optical communication side, with optical communication to enhance electronic computing proving itself to be the most useful and successful development.

There is a very sensible push in industry and research, that the focus should not be on the computation itself, but rather on the communication between compute elements[8]. Currently, the energy consumption of electronic communication happening on and off chip can reach over percent8080\%80 % of the total power consumption of an electronic processor[9, 10, 11]. By replacing these electronic wires with optical interconnects, one can expect an immediate efficiency gain of up to a factor of 666, due to waveguides being near lossless and highly efficient electro-optical modulation schemes. As an example, communicating a bit across an electronic chip can cost up to 600 fJ, whereas using electro-optical modulation would enable far lower energies, down to the 1-10 fJ domain[12], with the potential of reaching the attojoules in the coming years. The industry expects the majority of efficiency gains in the near future coming from such electro-optical hybrid computing approach, with both large companies, like Intel and Nvidia, as well as startups, like Lightmatter, Ayar Labs, Celestial AI and Black Semiconductor, actively developing schemes for optical interposers to connect electronic computing elements and memory. This development is highly beneficial not just for the field of computing, but also photonics in general.