This work presents recent advances in photorefractive polymer composites towards improved efficiency, speed, persistence of holograms and sensitivity at both visible and near infrared wavelengths. Besides the pure performance characteristics, a thin-device approach is presented to reduce operating voltage of these devices to practical levels and these materials are analyzed in both reflection and transmission geometries.The thin device operating at 1.3kV holds erasable, Bragg holograms with 80% efficiency in addition to its video-rate response time. The transition of hologram state from 'thick' to 'thin' is analyzed in detail. On the near IR portion of spectrum, new photorefractive polymer composites have been developed that enable high performance operation at 845nm and 975nm. Utilizing our novel photorefractive materials we demonstrate large diffraction efficiency in four-wave mixing experiments and video-rate response times. A major step towards achieving submillisecond response times is obtained through recording photorefractive gratings with individual nanosecond pulses at 532nm. At 4 mJ/cm2 illumination, a maximum diffraction efficiency of 56% has been obtained with a build-up time of only 300 microseconds (t1). This fast response enables applications in optical processing requiring frame rates of 100Hz or more. Due to the short duration of the writing pulses, the recording is insensitive to vibrations. Combining molecules that have different frontier orbital energies in a copolymer system and utilizing thermal fixing approach has led to long grating lifetimes of more than several hours. Later, in this dissertation, two low-glass-transition photorefractive polymer composites are investigated in reflection geometry. 60% is diffraction efficiency is observed in 105 micron thick devices of a PVK based composite. The reflection holograms are more sensitive to reading angle and slight birefringence due to the poling of chromophores has proven to cause a Bragg mismatch.

This work presents recent advances in the development of infra-red sensitive photorefractive polymers, and updateable near real-time holographic 3D displays based on photorefractive polymers. Theoretical and experimental techniques used for design, fabrication and characterization of photorefractive polymers are outlined. Materials development and technical advances that made possible the use of photorefractive polymers for infra-red free-space optical communications, and 3D holographic displays are presented.Photorefractive polymers are dynamic holographic materials that allow recording of highly efficient reversible holograms. The longest operation wavelength for a photorefractive polymer before this study has been 950nm, far shorter than 1550nm, the wavelength of choice for optical communications and medical imaging. The polymers shown here were sensitized using two-photon absorption, a third order nonlinear effect, beyond the linear absorption spectrum of organic dyes, and reach 40% diffraction efficiency with a 35ms response time at this wavelength. As a consequence of two-photon absorption sensitization they exhibit non-destructive readout, which is an important advantage for applications that require high signal-to-noise ratios.Holographic 3D displays provide highly realistic images without the need for special eyewear, making them valuable tools for applications that require "situational awareness" such as medical, industrial and military imaging. Current commercially available holographic 3D displays employ photopolymers that lack image updating capability, resulting in their restricted use and high cost per 3D image. The holographic 3D display shown here employs photorefractive polymers with nearly 100% diffraction efficiency and fast writing time, hours of image persistence, rapid erasure and large area, a combination of properties that has not been shown before. The 3D display is based on stereography and utilizes world's largest photorefractive devices (4x4 inch in size). It can be recorded within a few minutes, viewed for several hours without the need for refreshing and can be completely erased and updated with new images when desired, thusly comprising the first updateable holographic 3D display with memory, suitable for practical use.

This work presents the recent advances in photorefractive polymers for use in updatable holographic displays. A model with which to predict the effect of coplanar electrode geometry on diffraction uniformity in photorefractive (PR) polymer display devices was developed. Assumptions made in the standard use cases with constant electric field throughout the bulk of the media are no longer valid in the regions of extreme electric fields present in this type of device. Using electric field induced second harmonic generation (EFISHG) observed with multiphoton microscopy, the physical response in regions of internal electric fields which fall outside the standard regimes of validity were probed. Adjustments to the standard model were made, and the results of the new model were corroborated by holographic four-wave mixing measurements. The recent development of a single mode fiber-based pulsed laser with variable pulse length, energy, and repetition rate has enabled the characterization of photorefractive devices in a previously inaccessible regime located between millisecond and nanosecond pulse recording. A pulse width range of nine orders of magnitude opens the door to device and supporting laser optimization for use in video-rate holographic display. Device optimization has resulted in 5x improvement in single pulse four-wave mixing diffraction efficiencies to 10 - 11.5 % at pulse widths ranging between 6 ns and 100 µs. The grating recording time was likewise reduced by 5x to 16 ms at an applied bias of 72.5 V/μm. These improvements support 30 Hz update rates, which combined with the 3.3 - 10 kHz repetition rate pulsed laser, pave the way for real-time updatable holographic display.