Physics:Photoferroelectric imaging
Photoferroelectric imaging is the process of storing an image onto a piece of ferroelectric material by the aid of an applied electric pulse.
Stored images are nonvolatile and selectively erasable.[1] Photoferroelectric image storage devices have the advantage of being "extremely simple and easy to fabricate".[2]
Photoferroelectric imaging uses a ferroelectric material's photosensitivity in conjunction with its ferroelectric properties. One type of medium which has been used for photoferroelectric imaging is lead lanthanum zirconate titanate (PLZT) ceramics,[1] which exhibit a good combination of properties for imaging: large electro-optic coefficients, high intrinsic and extrinsic photosensitivities, and nonvolatile memory.[3]
Process
A description of a photoferroelectric imaging process (using PLZT material) is given in the McGraw-Hill Concise Encyclopedia of Science and Technology. In that process, a thin flat plate of transparent, optically polished PLZT material (around 0.25mm thick) was sputter-coated with indium tin oxide (ITO) on both sides, serving as electrodes. Then, the image was exposed onto one of the ITO surfaces, while a voltage pulse was simultaneously applied across the electrodes. The ferroelectric polarization thereby switched from one remanent state to another, and images were "stored both as spatial distributions of light-scattering centers in the bulk of the PLZT and as surface deformation strains which form a relief pattern of the image on the exposed surface."[1] The image may then be viewed directly or indirectly.[1]
This photoferroelectric effect is a type of electro-optic effect. In the example process, the ceramic was poled[lower-alpha 1] to a saturation remanent polarization state by the light (charge carriers were photoexcited across the PLZT's bandgap). The polarization was then switched by the application of the electric field - a phenomenon called photoassisted domain switching.[4]
Applications
Photoferroelectric imaging may be useful in temporary image storage and display.[1] It also has potential applications in data storage[5][4] and holographic recording.[4]
References
- ↑ 1.0 1.1 1.2 1.3 1.4 Land, Cecil (2004). "Photoferroelectric imaging". McGraw-Hill Concise Encyclopedia of Science and Technology (5 ed.). New York: McGraw-Hill.
- ↑ Cecil E. Land (8 April 1981). Photoferroelectric Image Storage in PLZT Ceramics (Report). Sandia National Labs. p. 1. https://apps.dtic.mil/sti/tr/pdf/ADA097448.pdf. Retrieved 4 April 2024. "PFE image storage devices are extremely sinple and easy to fabricate."
- ↑ D. Dimos and R. W. Schwartz (24 October 1991). "Electrooptic Properties of PZT Thin Films for Image Storage Applications". Materials Research Society. p. 73. doi:10.1557/PROC-243-73. https://link.springer.com/article/10.1557/PROC-243-73. "Transparent ferroelectric ceramics based on PLZT solid solutions, have been shown to exhibit a combination of properties, such as large electrooptic coefficients, high (intrinsic and extrinsic) photosensitivities, and nonvolatile memory, that make them suitable for optical information storage and processing applications."
- ↑ 4.0 4.1 4.2 Haertling, Gene H. (17 July 1986). "PLZT electrooptic materials and applications—a review 🔍". Ferroelectrics 75 (1): 41, 43. doi:10.1080/00150198708008208. https://www.tandfonline.com/doi/pdf/10.1080/00150198708008208. Retrieved 7 April 2024.
- ↑ "Storing information with light". 20 January 2021. https://phys.org/news/2021-01-storing-information-with-light.html.
Notes
- ↑ Poling means to align dipoles within a material.
See also
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