Novel geometrical model of photorefractive beam-fanning in barium titanate used to stabilize Double Phase Conjugation

摘要

As can be gathered from literature, photorefractive phase conjugation is inherently an unstable process, whether it be Simple or Double Phase Conjugation (DPC). In this article, a novel quasi-geometrical model of beam fanning, from which phase conjugation is said to stem, is proposed. Predicting the fanning pattern and thus the main fanning directions of both incident beams allows to make both the fanning patterns overlap naturally. This technique allows to suppress the would-be competition between fanning and DPC, thus reducing instabilities in the DPC process: an efficient and stable Double Phase Conjugate Mirror based on this approach in BaTiO_3 is demonstrated.