Focusing and phase conjugation of photon echoes in Na vapor

Abstract

The focusing and phase conjugation of photon echoes was observed in Na vapor. If the radius of curvature of the first pulse was R1 and the second pulse R2, the radius of curvature of the echo was given by 1/RE=2/R2−1/R1 and the echo center of curvature or focus followed from the phase φE(r) =2φ2(r)−φ1(r) in the Na cell.