There are longer wavelength amplification by stimulated emission of radiation (LASER without the L for light) devices but there are technological limitations li

There are longer wavelength amplification by stimulated emission of radiation (LASER without the L for light) devices but there are technological limitations like cavity size (often larger) and lower power. An example used in astronomy is the MASER: https://en.wikipedia.org/wiki/Maser https://en.wikipedia.org/wiki/Maser