In the radio part of the electromagnetic spectrum it is really easy to make very clean and powerful RF waves using modern electronics, and it really isn't that hard to make arbitrary RF waves.
But this type of electronic RF generation doesn't really have an equivalent on the optical side of the spectrum. With optical light you basically have to resort to using a laser to get anything close to a coherent and well-controlled light signal. On the other hand, you can do really amazing things with lasers, from quantum entanglement, to squeezed light used in LIGO to detect gravitational waves
So I was wondering, what non-trivial practical benefits would there be in having a radio-frequency laser? To be clear, I am not asking about how to make an RF laser, just about its potential uses and what those uses require. I'm also aware the microwave "maser" was the first laser. As an example of a possible use, I would imagine that a RF laser that could be operated in quantum-limited state would be very useful for superconducting quantum computers.