Total Internal Reflection

Back in college, I learned a neat principle about the index of refraction. If you go from a lower to a higher index of refraction, you get reflection. If this is just right, like in the case of a fiber-optic cable, surrounded by a cladding, you get total internal reflection.

Do they have devices like cubes that can create a plane of changing index, to simulate what a mirror on a galvo would do, but without any moving parts? If this could be purely optical, then it might be able to vastly exceed the 40k rate.

There are certain setups called Optical Parametric Oscillators that I did a paper on in college. IIRC, by using magentic fields in a certain orientation, the signal and idler lights could be adjusted to tune the laser output. However, that only worked for pulsed lasers.

So if the index could be used, it could create possibly the best reflection with minimum loss.