Modulational instability of optical beams in photorefractive media due to two-wave or parametric four-wave mixing effects

Abstract

Modulational instability in a photorefractive medium is studied in the presence of two wave mixing. We then propose and derive a model for forward four wave mixing in the photorefractive medium and investigate the modulational instability induced by four wave mixing effects. By using the standard linear stability analysis the instability gain is obtained. In both the cases, the geometry is such that the effect of self-phase-modulation self-focusing is suppressed and only the holographic focusing nonlinearity is acting.

Modulation instability of plane electromagnetic beams in centro-symmetric crystals due to two-photon photorefractive effects

“…Investigations of MI have been performed extensively in a wide range of physical systems such as fluids [1], plasmas [2][3][4], Bose Einstein condensates [5,6], discrete nonlinear systems [7,8], negative index materials [9,10], soft matter [11], nonlinear optical systems such as photorefractive (PR) media [12][13][14], optical fibers [15,16], etc. It is important to note that MI typically occurs in the same parameter region where another optical phenomenon, the soliton, is observed.…”