# Can an electromagnetic wave be split into multiple longer wavelength waves?

Is there any way to convert short wavelength (visible light/near infrared) electromagnetic waves into multiple long wavelength waves (microwave) of near equal total energy?

Heating a blackbody with short wavelength light and letting it emit its energy in longer wavelengths is the best way I can imagine doing this. But, if I'm correct, most of the energy emitted by blackbodies is <20μm above room temperature. Is there anything that will emit most of its energy at >300μm? Can this be done with some kind of multiple photon emission from a single electron transition?

One possibility is so called optical parametric amplification (OPA), which basically splits a photon with frequency $\omega_0$ in two photons with frequency $\omega_i$ and $\omega_s$ with $\omega_0 = \omega_i+\omega_s$. This however only works nicely for high intensities i.e. pulsed light sources.
I could imagine a molecule which has two states $E_1$ and $E_2$ above his groundstate with $|E_1| < |E_2|$. A photon could excite the molecule to $E_2$ and the molecule would first fall into $E_1$ and then into the ground state. If $E_2$ is something like two times $E_1$ you would have two emitted photons with a smaller wavelength than the one photon that excited the molecule.