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Current hybrid photorefractive cells have been successful, but the potential benefits of the technology have been limited by the relatively small magnitude of the available evanescent space-charge field. Great improvements to the hybrid device performance are possible if either the field can be increased significantly, or if the sensitivity of the adjacent liquid crystal layer to the influence of the electric field can be improved. One example of such hybrid device would include a liquid crystal layer with a 45 degree pre-tilt, with preferably a low anchoring energy. In devices where charge migration is dominated by diffusion and also in situations where the application of external electric fields is undesirable, increasing the sensitivity of the liquid crystal layer to the space charge field is the most practical method for improving device performance. As such, there is a need for improved photorefractive hybrid cells.
Air Force scientists have developed hybrid photorefractives that include one or more windows and one or more adjacent layers of gain media. The gain media may be a liquid crystal or a polymer material that includes nanoparticles and those nanoparticles may be any solid or gel and either active or passive (and inorganic or organic) in nature. For example, the nanoparticles may be ferroelectric nanoparticles. Nanoparticles have a pronounced effect on the gain characteristics, sensitivity, birefringence, speed and photorefractive beam coupling of the hybrid cell. Additionally, the invention permits transient or steady state optical interactions with thermally absorbed radiation, optical fields, acoustic radiation, and induced electrostriction.
US patent 8,369,006 is a divisional of US patent 8,018,648.
- Nanoparticles dramatically influence the optical gain characteristics, increasing the magnitude of the gain and reversing the sign of the beam coupling
- The particles may be added directly to a liquid or polymer pre-cursor (monomer), or they may be pre-treated or coated with other substances to promote better solubility, discourage aggregation, or to add functionality to the nanoparticles
- US patent 8,369,006 available for license