Scattering Effects Caused By One-dimensional Gratings In Photorefractive Crystal LiNbO₃:Fe

Light-induced scattering is a kind of special phenomenon,it is that when the electro-optic material is irradiated,its scattered light is amplified due to the photorefractive effect,then the scattered light write to the noise phase grating,through the noise phase grating diffraction,the incident light energy transfer,thus amplifying the scattered light.In this paper,we used the typical photorefractive crystal—iron-doped lithium niobate,observed the special scattering phenomenon and characteristics of the photorefractive effect.Including the relationship with the polarization of the incident light,irradiation time,the angle between the crystal C-axis orientation.Light-induced scattering is widespread phenomenon in a photorefractive crystal,it have a wide range of applications such as optical communications,Interferometer,optical processing,laser coupling and its lock and other fields.According to the research goal,the work has mainly carried on the following four aspects.1.Firstly,we introduce the physical mechanism of photorefractive effect,the main characteristics,the main features of the typical crystal LiNbO₃: Fe and the light scattering.2.We observe special scattering light by using a simple experimental device and record the dynamic behavior with a camera.On condition that the directions of line beam?f?and c-axis of the crystal are both parallel to the horizontal direction,we observe experimentally that the scattering light spreads gradually in the horizontal direction in the far field as irradiation time goes on.When the line beam is horizontal and the c-axis is vertical,the scattering light composed of horizontal filaments firstly appears in the vertical direction.About 30 min later,the scattering light appears and spreads along the horizontal direction to the far field as irradiation time goes on.At this time,the scattering light is also composed of vertical filaments.3.We observe special scattering light by the same experimental device with the extraordinary light,we find that the scattering light is appear alone the line beam,Vertical to the line beam and the c-axis of the crystal.4.We observe special scattering light by the same experimental device with the Ordinary polarized light,we find that when the angle between c-axis of the crystal and beam angle less than 45 °,the scattering phenomenon can be observed;when the angle between c-axis of the crystal and beam angle is greater than or equal to 60 °,there is only a weak beam fanning can be seen.