Incoming links: Lightmatter
Some of the earlier computers of the 20th centure were analog computers, not digital.
At some point analog died however, and "computer" basically by default started meaning just "digital computer".
As of the 2010's and forward, with the limit of Moore's law and the rise of machine learning, people have started looking again into analog computing as a possile way forward. A key insight is that huge floating point precision is not that crucial in many deep learning applications, e.g. many new digital designs have tried 16-bit floating point as opposed to the more traditional 32-bit minium. Some papers are even looking into 8-bit: dl.acm.org/doi/10.5555/3327757.3327866
As an example, the Lightmatter company was trying to implement silicon photonics-based matrix multiplication.
A general intuition behind this type of development is that the human brain, the holy grail of machine learning, is itself an analog computer.
Silicon Photonics: The Next Silicon Revolution? by Asianometry (2022)
Source. - youtu.be/29aTqLvRia8?t=714 GlobalFoundries seems to be one of the leaders at the time. E.g. quantum computing company PsiQuantum uses them. Part of this was from acquiring IBM's microelectronics division in 2014.
Running Neural Networks on Meshes of Light by Asianometry (2022)
Source. - youtu.be/t0yj4hBDUsc?t=440 block diagram
- youtu.be/t0yj4hBDUsc?t=456 Lightmatter lightmatter.co/ seems to be using an in-silicon Mach-Zehnder interferometer to do analog matrix multiplication with light. It is an actual analog computer element!