Highly efficient rewritable thin polarization holograms through paraxial recording in azo-carbazole copolymer-based composite films†

Polarization holography has emerged as a promising technique for high-density data storage, security, and optical communication applications. In this study, thin-polarization gratings have gained significant attention because of their superior optical properties, such as high diffraction efficiency, polarization selectivity, and a high signal-to-noise ratio. This paper investigates thin circular polarization holograms within an azo-carbazole copolymer-based composite film. Our findings show an outstanding diffraction efficiency of over 90% in circular polarization holograms, even with a low-intensity writing beam and a few seconds writing time. The recorded hologram shows a high retention time of more than 50 days with a retention ratio of more than 50% when stored at a low temperature in the dark. We conducted a thorough analysis of the polarization characteristics of the diffracted beam in both circular and linear polarization holograms, which we applied to polarization multiplexing applications. We evaluated the rewritable property of the material and successfully recorded and erased more than 60 holograms in less than 10 min. This study comprehensively analyzes thin polarization holograms within an azo-carbazole copolymer-based composite film and highlights their potential for use in various applications.