Dark decay dynamic behavior of field-induced photorefractive grating in a Mn:Fe:KTN co-doped crystal

In this paper, we study the dark decay dynamic behavior of field-induced photorefractive (PR) grating in a Mn:Fe:KTN crystal under different conditions. The spatial distribution and temporal evolutions of field-induced PR grating dark decay are visualized in situ and monitored quantitatively by means of digital holographic microscopy. Subsequently, the dark decay time of phase grating can be achieved according to the dynamic behavior, which can be improved drastically by a writing field and is insensitive to the grating period. The mechanism of enhanced lifetime of grating is interpreted by the potential well model. The external field enhances the growth of polar nanoregions, forming a potential well that binds the carriers, ultimately prolonging the dark decay time. This work provides an effect way for enhancing lifetime of PR grating, which can be very useful for a variety of applications, including PR storage and holographic optical elements.