Bumped into this company some years ago that use light to perform 'random projection', which can be used to approximate matrix multiplication. Which is used a lot in the AI space (reduction of dimension etc)

How? They do the projection quite literally: with DLP projectors that project on CCD through a 'dirty' medium, for randomness. At current DLP resolutions and refresh rates, every pixel being one bit, I'll let you imagine how much data you can push through, using only 30W. The whole thing is sold as an appliance, a sort of co-processor that can do just one operation (but a really complex one)

They released their first commercial product a couple of months ago, hope it works out for them as the idea sounds pretty amazing.

edit: found their website https://lighton.ai/