OSA's Digital Library

Applied Optics

Applied Optics


  • Vol. 37, Iss. 35 — Dec. 10, 1998
  • pp: 8181–8186

Optical encryption system that uses phase conjugation in a photorefractive crystal

G. Unnikrishnan, Joby Joseph, and K. Singh  »View Author Affiliations

Applied Optics, Vol. 37, Issue 35, pp. 8181-8186 (1998)

View Full Text Article

Enhanced HTML    Acrobat PDF (107 KB)

Browse Journals / Lookup Meetings

Browse by Journal and Year


Lookup Conference Papers

Close Browse Journals / Lookup Meetings

Article Tools



We implement an optical encryption system based on double-random phase encoding of the data at the input and the Fourier planes. In our method we decrypt the image by generating a conjugate of the encrypted image through phase conjugation in a photorefractive crystal. The use of phase conjugation results in near-diffraction-limited imaging. Also, the key that is used during encryption can also be used for decrypting the data, thereby alleviating the need for using a conjugate of the key. The effect of a finite space–bandwidth product of the random phase mask on the encryption system’s performance is discussed. A theoretical analysis is given of the sensitivity of the system to misalignment errors of a Fourier plane random phase mask.

© 1998 Optical Society of America

OCIS Codes
(070.1170) Fourier optics and signal processing : Analog optical signal processing
(070.2590) Fourier optics and signal processing : ABCD transforms
(160.5320) Materials : Photorefractive materials
(190.4380) Nonlinear optics : Nonlinear optics, four-wave mixing
(190.5040) Nonlinear optics : Phase conjugation
(330.6110) Vision, color, and visual optics : Spatial filtering

Original Manuscript: April 1, 1998
Revised Manuscript: August 27, 1998
Published: December 10, 1998

G. Unnikrishnan, Joby Joseph, and K. Singh, "Optical encryption system that uses phase conjugation in a photorefractive crystal," Appl. Opt. 37, 8181-8186 (1998)

Sort:  Author  |  Year  |  Journal  |  Reset  


  1. B. Javidi, J. L. Horner, “Optical pattern recognition for validation and security verification,” Opt. Eng. 33, 1752–1756 (1994). [CrossRef]
  2. P. Réfrégier, B. Javidi, “Optical image encryption based on input plane and Fourier plane random encoding,” Opt. Lett. 20, 767–769 (1995). [CrossRef] [PubMed]
  3. B. Javidi, G. S. Zhang, J. Li, “Encrypted optical memory using double-random phase encoding,” Appl. Opt. 36, 1054–1058 (1997). [CrossRef] [PubMed]
  4. B. Javidi, G. Zhang, J. Li, “Experimental demonstration of the random phase encoding technique for image encryption and security verification,” Opt. Eng. 35, 2506–2512 (1996). [CrossRef]
  5. L. G. Neto, Y. Sheng, “Optical implementation of image encryption using random phase encoding,” Opt. Eng. 35, 2459–2463 (1996). [CrossRef]
  6. E. L. Kral, J. F. Walkup, M. O. Hagler, “Correlation properties of random phase diffusers for multiplex holography,” Appl. Opt. 21, 1281–1290 (1982). [CrossRef] [PubMed]
  7. T. F. Krile, R. J. Marks, J. F. Walkup, M. O. Hagler, “Holographic representations of space-variant systems using phase-coded reference beams,” Appl. Opt. 16, 3131–3135 (1977). [CrossRef] [PubMed]
  8. P. Yeh, Introduction to Photorefractive Nonlinear Optics (Wiley, New York, 1993), Chap. 4.
  9. L. Solymar, D. J. Webb, A. Grunnet-Jepson, The Physics and Applications of Photorefractive Materials (Clarendon, Oxford, 1996).
  10. J. Joseph, K. Singh, P. K. C. Pillai, “A new phase conjugate scheme for one way imaging through phase distorting media,” Appl. Phys. B. 51, 219–221 (1990). [CrossRef]
  11. J. Widjaja, Y. Tomita, “Optical triple-in digital logic using nonlinear optical four-wave mixing,” Appl. Opt. 34, 5074–5076 (1995). [CrossRef] [PubMed]
  12. A. D. Meigs, B. E. A. Saleh, “Spatial fidelity of photorefractive image correlators,” IEEE J. Quantum Electron. 30, 3025–3032 (1994). [CrossRef]
  13. P. Xie, J.-H. Dai, P.-Y. Wang, H.-J. Zhang, “Spatial fidelity of externally pumped phase conjugation in photorefractive crystals,” J. Opt. Soc. Am. B 14, 852–859 (1997). [CrossRef]
  14. J. Joseph, K. Singh, P. K. C. Pillai, “Crystal orientation dependence of SNR for signal beam amplification in photorefractive BaTiO3,” Opt. Laser Technol. 23, 237–240 (1991). [CrossRef]

Cited By

Alert me when this paper is cited

OSA is able to provide readers links to articles that cite this paper by participating in CrossRef's Cited-By Linking service. CrossRef includes content from more than 3000 publishers and societies. In addition to listing OSA journal articles that cite this paper, citing articles from other participating publishers will also be listed.


Fig. 1 Fig. 2 Fig. 3

« Previous Article  |  Next Article »

OSA is a member of CrossRef.

CrossCheck Deposited