Frequency down-conversion through Bose condensation of light

We propose an experimental setup allowing one to convert an input light of wavelengths about 1-2 mum into an output light of a lower frequency. The basic principle of operation relies on the nonlinear optical properties exhibited by a microcavity filled with a photonic bandgap material. The light inside this material behaves like an interacting Bose gas susceptible to reach thermal equilibrium and create a Bose-Einstein condensate. Theoretical estimations show that using a fiber grating, a conversion of 1 mum into 1.5 mum is achieved with an input pulse of about 1 ns, and characterized by a peak power of 10(3) W.