  Starting from a frequency diffusion process for a tagged photon which
simulates relaxation to the Planck law, we introduce a resetting where photons
lower their frequency at random times. We consider two versions, one where the
resetting to low frequency is independent of the existing frequency and a
second case where the reduction in frequency scales with the original
frequency. The result is a nonlinear Markov process where the stationary
distribution modifies the Planck law by abundance of low-frequency occupation.
The physical relevance of such photon resetting processes can be found in
explorations of nonequilibrium effects, e.g., via random expansions of a
confined plasma or photon gas or via strongly inelastic scattering with matter.
