[zifk]

This feels like lazy reporting. One beam isn't blocking the other, it's inducing a localized nonlinear process in a material which then absorbs the crossing beam. This isn't a novel process.

It's like me saying if I close a door I'm casting a shadow, sure, I caused it, but it's not my shadow.

[mikewarot]

I was about to say the same thing... unless they can do this in vacuum, it's a curiosity, but not something novel.

[magicalhippo]

Intense laser light can cause electron-positron pair production[1], but we're not quite there yet AFAIK.

[1]: https://en.wikipedia.org/wiki/Breit%E2%80%93Wheeler_process

[Dylan16807]

Now do it without moving the door. That's what makes this interesting. It uses the crystal, but it's not changing the crystal.

[Narew]

It's changing the crystal not the structure but the state. Ruby crystal are gained medium for laser https://en.wikipedia.org/wiki/Ruby_laser you can pumped them with light.

[mannykannot]

I suppose one could say that opening a second path in an interferometer also 'casts a shadow', though by a different mechanism.

This sort of usage does not bother me (at least at what I perceive as this benign level.) Metaphor and simile are part of the expressive power of human language, and both writing and reading would become tedious if we tried to eliminate them.