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Fulgide is well-known as a thermally irreversible organic photochromic compound. The fulgide films can be applied as recording materials in ordinary holography and polarization holography, which were respectively based on the photochromic and photoinduced anisotropy properties. In this report, different kinds of multiplexing holographic storage, like angle multiplexing, circumrotation multiplexing and polarization multiplexing are realized in a 3-indoly-benzylfulgimide/ PMMA film for the first time, where 5 images, 18 images and 2 images are stored at the same position of the film, and diffracted without crosstalk with each other. It is proved that 3-indoly-benzylfulgimide film has spatial resolution of 6300lines/mm, sensitivity of 2.89 × 10-3cm2/mJ at 632.8nm on the polarization direction of the exciting beam, fatigue resistance of 70 times, thermal stability of 14 months and has advantages like low cost, easy to used, rewritable, long life time at room temperature for both states, and high signal to noise ratio. Overall, 3-indoly-benzylfulgimide is a better rewritable holographic storage medium, but the fatigue resistance and thermal stability should be improved.

A synthesized photochromic compound--pyrrylfulgide--is prepared as a thin film doped in a polymethylmethacrylate (PMMA) matrix. Under irradiation by UV light, the film converts from the bleached state into a colored state that has a maximum absorption at 635 nm and is thermally stable at room temperature. When the colored state is irradiated by a linearly polarized 650 nm laser, the film returns to the bleached state; photoinduced anisotropy is produced during this process. Application of optical image processing methods using the photoinduced anisotropy of the pyrrylfulgide/PMMA film is described. Examples in non-Fourier optical image processing, such as contrast reversal and image subtraction and summation, as well as in Fourier optical image processing, such as low-pass filtering and edge enhancement, are presented.

Optical films containing the genetic variant bacteriorhodopsin BR-D96N were experimentally studied in view of their properties as media for holographic storage. Different polarization recording schemes were tested and compared. The influence of the polarization states of the recording and readout waves on the retrieved diffractive image’s intensity and its signal-to-noise ratio were analyzed. The experimental results showed that, compared with the other tested polarization relations during holographic recording, the discrimination between the polarization states of diffracted and scattered light is optimized with orthogonal circular polarization of the recording beams, and thus a high signal-to-noise ratio and a high diffraction efficiency are obtained. Using a He–Ne laser (633 nm, 3 mW) for recording and readout, a spatial light modulator as a data input element, and a 2D-CCD sensor for data capture in a Fourier-transform holographic setup, a storage density of 2 × 10^8 bits/cm was obtained on a 60 × 42 µm^2 area in the BR-D96N film. The readout of encoded binary data was possible with a zero-error rate at the tested storage density.

In polymeric films of bacteriorhodopsin (BR) a photoconversion product, which was named the F620 state, was observed on excitation of the film with 532?nm nanosecond laser pulses. This photoproduct shows a strong nonlinear absorption. Such BR films can be used for write-once–read-many (WORM) optical data storage. We demonstrate that a photoproduct similar or even identical to that obtained with nanosecond pulses is generated on excitation with 532?nm femtosecond pulses. This photoproduct also shows strong anisotropic absorption, which facilitates polarization storage of data. The product is thermally stable and is irretrievable to the initial B state either by photochemical reaction or through a thermal pathway. The experimental results indicate that the product is formed by a two-photon absorption process. Optical WORM storage is demonstrated by use of two polarization states, but more polarization states may be used. The combination of polarization data multiplexing and extremely short recording time in the femtosecond range enables very high data volumes to be stored within a very short time.

In polymeric films of bacteriorhodopsin (BR) a photoconversion product, which was named the F620 state, was observed on excitation of the film with 532 nm nanosecond laser pulses. This photoproduct shows a strong nonlinear absorption. Such BR films can be used for write-once-read-many (WORM) optical data storage. We demonstrate that a photoproduct similar or even identical to that obtained with nanosecond pulses is generated on excitation with 532 nm femtosecond pulses. This photoproduct also shows strong anisotropic absorption, which facilitates polarization storage of data. The product is thermally stable and is irretrievable to the initial B state either by photochemical reaction or through a thermal pathway. The experimental results indicate that the product is formed by a two-photon absorption process. Optical WORM storage is demonstrated by use of two polarization states, but more polarization states may be used. The combination of polarization data multiplexing and extremely short recording time in the femtosecond range enables very high data volumes to be stored within a very short time.