Instantaneous characteristics study of the diffracted and transmitted light of a staticphotorefractive reflection volume holographic grating read by an ultrashort pulselaser

Abstract

The time-domain diffraction and transmission of reflectionvolume holographic gratings (RVHGs) recorded in photorefractiveLiNbO3 crystals are theoretically studied and compared with transmission volume holographicgratings (TVHGs) when they are illuminated by ultrashort pulse laser light. The modifiedKogelnik’s coupled-wave theory, combining the dispersion effect in the crystal, is used.The results show that larger diffraction intensity can be obtained by choosing alarger grating period, grating thickness and modulation index for a given pulseduration. The RVHG has higher diffraction intensity than the TVHG with thesame grating parameters. Also, it is found that the diffracted pulse of the RVHGand the TVHG shift in opposite directions along the time-axis. The values ofthe shifts are functions of the readout pulse duration and grating parameters.The overmodulation phenomenon appears in the diffracted pulse of the TVHGat high values of the grating thickness and refractive index modulation, but itdoes not occur in the RVHG. The results of our study can be used in choosingproper grating parameters for pulse shaping and signal processing applications.