Hans-Peter Wagner

University of Cincinnati

"Exciton induced phase coherent photorefractivity in

ZnSe single quantum wells"

There has been substantial interest in controlling and conserving coherent optical pulses in solids to uncover new physical phenomena and for potential applications like optical data storage and quantum computation. Important building blocks towards this goal are photorefractive (PR) devices that are capable of preserving coherent optical information. Present PR devices reveal high sensitivity and fast response but they require externally applied electric fields and do not use the coherence of excitons to conserve the phase and polarization information of incident light fields. We observe an exciton resonant phase coherent photorefractive (PCP) effect in ZnSe single quantum wells (QWs) using ultra-short light pulses that do not overlap in time. The PCP effect is attributed to the formation of an electron grating within the QW formed by the interference of coherent excitons. Since coherent excitons can be regarded as ultraslow light, the phase and polarization of incident light fields can be stored and released by a delayed reading pulse at later time. The high diffraction efficiency of PCP makes it attractive for optical data processing where the angular momentum of incident photons provides an additional degree of information. In addition, PCP has potential for holographic optical coherent imaging (OCI) for industrial and medical purposes.

Thursday, April 13, 2006

4:10 p.m. -- Walter Lecture Hall 245