Efficient ir image up-conversion in two-photon resonantly pumped Cs vapor

Abstract
Resonant two‐photon pumping in the Cs 6s2S‐7s2S transition has been used for 2.9 μm to 4550 Å image up‐conversion. A power conversion efficiency of 20% with 1000 resolvable spots was achieved using a pump power of 8 kW. The pumping laser, Nd : lanthanum berylate, has a natural two‐photon coincidence with the Cs 6s2S‐7s2S transition.