I disagree with the OP's inference that the diffraction effect is "digital" because it produces discrete, light and dark, positively and negatively reinforced interference patterns.

Assuming it were true, such a whole number unity effect would not be properly termed"digital" but rather an artifact of Boolean logic. It would be "Boolean," not "digital".

But of course, the diffraction of photons is a wave-like phenomenon, governed not by Boolean principles at all, and is most decidedly "analog" in nature, in the sense that multiple waves interfering with one another out of phase produce additive and subtractive vectors whose output space might resemble some discrete function only superficially, absent a deeper understanding of the underlying principles.