> seamlessly connected to optical waves that oscillate at 10,000 times higher frequencies
Somehow four orders of magnitude sound too less for the transition from radio to light, but it makes sense. A i9 processor works at ~6 GHz, and light is at the THz range
Microwave communication goes comfortably into the tens of gigahertz range, and visible light is in the hundreds of terahertz. So it is about a factor of 10,000.
"Effective" compared to the state of the art in the bands on either side: in RF/microwave we have very fast arbitrary waveform generators, very nice amplifiers, and well-characterized conductors, and on the optical side we have lasers, lights, fibers, and more. The terahertz gap is so named because it's too high in frequency for our usual RF devices to work well, and too low in frequency for our usual optical devices to work well; terahertz work ends up being a mix of both, taking from either column as needed for a specific application. (You might hear the word "quasi-optical" used in this sense, though I've never heard the dual word "quasi-microwave"!)
We do have terahertz devices - they're just very limited compared to devices in adjacent bands, usually stated in terms of power. But there are a lot of hardworking and talented people working on narrowing the THz gap from all sides. It's a very very hot research area at the moment.
Comparing CPU frequency (tens of thousands individual lanes that have to be skew-matched) to single-path stuff is quite apples to oranges.
Processor frequency is mostly limited by interconnect and cooling (and silicon, but there are other materials available, it's just not worth switching to those unless you solve cooling). Even thunderbolt transceivers go 40GT/lane=20GHz and that's consumer tech. With InP you can go slightly above 100GHz afaik.
Somehow four orders of magnitude sound too less for the transition from radio to light, but it makes sense. A i9 processor works at ~6 GHz, and light is at the THz range