COUPLING OF MUTUALLY INCOHERENT BEAMS IN PHOTOREFRACTIVE BI12TIO20 FIBER

A novel geometry of double phase conjugate mirror in photorefractive s ingle crystal Bi12TiO20 fiber is proposed, when pump beams are repeate dly internally reflected from the fiber faces. The phase conjugate wav e reflectivities up to 18% and with response time of a few seconds wer e obtained at lambda = 632.8 nm, supplying the fiber with an alternati ng electric field of square wave form. Two possible effective configur ations of mutually incoherent beam coupling inside the photorefractive fiber were compared experimentally.