I met someone in Seattle who was working on an optical Asic to mine Bitcoin. Is this in the same direction as this article?
That said, photonic gates for digital circuits hold some promise for power efficiency and speed in their own way. For many of the parameters which apply to crypto mining, it's not so clear whether photonic digital circuits will significantly outperform the best near-future electronic transistors though.
(Source: I worked on a photonic crypto circuit design based on 4-wave (non-linear) mixing. Non-linearity is required for digital logic. Even though 4-wave mixing is energy efficient, the design was less efficient and performant than I'd initially hoped from the high spatial parallelism and basic THz figures. The principles still hold a lot of promise.)
Now for some specific operations optical signal processing might still make sense, for example if you can take advantage of the bandwidth and inherent parallism.