Fractional Fourier transform dual random phase encoding of time-varying signals |
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Authors: | C Cuadrado-Laborde R Duchowicz EE Sicre |
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Institution: | a Centro de Investigaciones Ópticas (CONICET-CIC), Camino Centenario entre 505 y 508, P.O. Box 124, 1900 La Plata, Buenos Aires, Argentina b Departamento de Física Aplicada, Universidad de Valencia, Dr. Moliner 50, 46100 Valencia, Spain c Facultad de Ingeniería y Ciencias Exactas, Universidad Argentina de la Empresa (UADE), Lima 717, 1073 Buenos Aires, Argentina |
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Abstract: | Optical techniques have shown great potential in the field of information security to encode high-security images. Among several established methods, a double-random phase encryption technique (DRPE) for encoding a primary image into stationary white noise was developed by using the analogy between Fresnel diffraction patterns and the fractional Fourier transform (FrFT-DRPE). In this case, additional keys are obtained through the knowledge of the fractional orders of the FrFTs. In this work we propose an encoding setup for time-varying signals, mainly for short-haul fiber optics link applications, that can be considered as the temporal analogue of the spatial FrFT-DRPE. The behavior of the proposed method is analyzed by employing the Wigner distribution function. As a result, general expressions for both signal time width and spectral bandwidth, at all encryption stages are obtained. Numerical simulations have been carried out to illustrate the system performance. The obtained results indicate that this encryption method could be a good alternative to other well-established methods. |
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Keywords: | Optical fibers Encryption Fractional Fourier transform |
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