I'm not personally familair with the term, particualrly in a context of lasers, but it does make sense.

I'd consider re-writing, though, to something like "beating togther two lasers of (slightly) differing frequencies" — the rest of your context may make it clearer whether this would be a viable somution or not; it relly all depends just how different the frequencies are, or whether they are so close, they're not really meant to be 'different' at all.