Gravitational signals cover all the same frequencies are electromagnetism
At https://www.emf-corp.com/optical-materials/optical-material-infrared-optics/ please use the empty space to extend to 1E15 meters to cover low fruquency electromagnetic and gravitational wavelenghts. In frequency units 1 nanoHertz has a wavelength of 2.99792458E17 meters or 1E9 Light Seconds. I am looking for LWIR and longer wavelength lens materials. Since I work a lot with gravitational sensors, it always bothers me to see people chop the spectrum off just when it gets interesting. The earth moon distance is about 1.28 light seconds, and earth diameter is about 0.0425 light seconds. There are people who work on problems pico and femtoHertz. The age of the universe corresponds to 2.29 attoHertz. Gravitational signals cover all the same frequencies are electromagnetism.