I would say, forget that Bloomberg (“they use waveguides”) article, and instead read the text from Lightmatters on Medium, which is referenced by the Bloomberg article.

It shows that Lightmatters seems to have a lot of experience regarding artificial intelligence (AI) processors, particularly matrix multiplication with light, a domain POET Technologies is only about to enter and has no experience in.

Pure speculation of course, but I would not be too surprised if there’s already some form of collaboration. Lighmatters seems to be looking for partners. At least you could understand the closing paragraph of the article this way:

“We look forward to sharing our ultra-fast, efficient optical compute platform with companies that, like us, are looking to push the boundaries of what is possible with responsible artificial intelligence.”