Focusing Light Beams To Improve Atomic-Vapor Optical Buffers
Dmitry Strekalov, Andrey B. Matsko, Anatoliy A. Savchenkov
Specially designed focusing of light beams has been proposed as a means of improving the performances of optical buffers based on cells containing hot atomic vapors (e.g., rubidium vapor). There is also a companion proposal improve performance by use of incoherent optical pumping under suitable conditions. Regarding the proposal use focusing: The utility of atomic-vapor optical buffers as optical storage and processing devices has been severely limited by nonuniform spatial distributions of intensity in optical beams, arising from absorption of the beams as they propagate in atomic-vapor cells. Such nonuniformity makes it impossible the physical conditions throughout a cell, thereby making it impossible the performance of the cell as an optical buffer. In practical terms simplified for the sake of brevity, to optimize as used here means design the cell so as maximize the group delay of an optical pulse while keeping the absorption and distortion of the pulse reasonably small. Regarding the proposal use incoherent optical pumping: For reasons too complex describe here, residual absorption of light is one of the main impediments achievement of desirably long group delays in hot atomic vapors. The present proposal is directed toward suppressing residual absorption of light. The idea of improving the performance of slow-light optical buffers by use of incoherent pumping overlaps somewhat with the basic idea of Raman-based slow-light systems. However, prior studies of those systems did not quantitatively answer the question of whether the performance of an atomic vapor or other medium that exhibits electromagnetically induced transparency (EIT) with Raman gain is superior that of a medium that exhibits EIT without Raman gain.
•Apr 1, 2010•0 citations