Efficient phase conjugation using Raman dark resonances in an optically dense crystal

Summary form only given. In a three-level system, optical refractive indices can be changed due to the atom-field interactions. Especially in a short time scale (t/spl Lt/ /spl gamma/), a resonant strong electromagnetic field can change the absorption coefficient strongly so that another resonant electromagnetic field which has a different frequency can pass through without experiencing any absorption in an optically dense medium. This phenomenon is called electromagnetically induced transparency (EIT). There have been many studies of EIT in atomic vapors and solids for potential applications to nonlinear optical processes such as enhanced four-wave mixing, lasers without inversion, frequency up-conversion lasers, and optical memory. We report efficient phase conjugation based on EIT in an in homogeneously broadened solid system of Pr/sup 3+/ doped yttrium silicate.