Ghost imaging-based optical cryptosystem for multiple images using integral property of the Fourier transform

A novel ghost imaging-based optical cryptosystem for multiple images using the integral property of the Fourier transform is proposed.Different from other multiple-image encryption schemes,we mainly construct the modulation patterns related to the plaintext images to realize the encrypted transmission of multiple images.In encryption process,the first image is encrypted by the ghost imaging encryption scheme,and the intensity sequence obtained by the bucket detector is used as the ciphertext.Then modulation patterns of other images are constructed by using the integral property of the Fourier transform and used as the keys.Finally,the ciphertext and keys are transmitted to the receiver to complete the encryption process.During decryption,the receiver uses different keys to decrypt the ciphertext and gets different plaintext images,and decrypted images have no image aliasing problem.Experiments and simulations verify the feasibility,security,and robustness of the proposed scheme.This scheme has high scalability and broad application prospect,which provides a new idea for optical information encryption.

Polarization-independent highly efficient generation of Airy optical beams with dielectric metasurfaces

Airy optical beams have emerged to hold enormous theoretical and experimental research interest due to their outstanding characteristics.Conventional approaches suffer from bulky and costly systems,as well as poor phase discretization.The newly developed metasurface-based Airy beam generators have constraints of polarization dependence or limited generation efficiency.Here,we experimentally demonstrate a polarization-independent silicon dielectric metasurface for generation of high-efficiency Airy optical beams.In our implementation,rather than synchronous manipulation of the amplitude and phase by plasmonic or Huygens’metasurfaces,we employ and impose a 3/2 phase-only manipulation to the dielectric metasurface,consisting of an array of silicon nanopillars with an optimized transmission efficiency as high as 97%.The resultant Airy optical beams possess extraordinarily large deflection angles and relatively narrow beam widths.Our validated scheme will open up a fascinating doorway to broaden the application scenarios of Airy optical beams on ultracompact photonic platforms.

One-to-many optical information encryption transmission method based on temporal ghost imaging and code division multiple access

A method is presented for one-to-many information encryption transmission by using temporal ghost imaging and code division multiple access.In the encryption transmission process,code division multiple access technologies combine multiple information sources,and the chip sequence corresponding to each set of information is used as the first key.The transmission end loads the transmission information onto a series of temporal random patterns of temporal ghost imaging and transmits it to the receivers.A series of temporal random patterns is the second key.During the decryption,each receiver can get the same encrypted information and use the second key to obtain the transmitted information.Finally,each receiver uses the unique chip sequence to get corresponding information.This encryption transmission method realizes one-to-many information encryption transmission at the same time over the same channel.Double encryption ensures the security of information.Simulation and experiment results verify the effectiveness and security of the method.The method has strong antinoise ability and can effectively resist various attack modes.At the same time,this method solves the problem that the use of code division multiple access enlarges the signal bandwidth,and ensures that no cross talk occurs between various sources of information.

Study on the key technology of spectral reflectivity reconstruction based on sparse prior by a single-pixel detector

By studying the traditional spectral reflectance reconstruction method, spectral reflectance and the relative spectral power distribution of a lighting source are sparsely decomposed, and the orthogonal property of the principal component orthogonal basis is used to eliminate basis; then spectral reflectance data are obtained by solving a sparse coefficient. After theoretical analysis, the spectral reflectance reconstruction based on sparse prior knowledge of the principal component orthogonal basis by a single-pixel detector is carried out by software simulation and experiment. It can reduce the complexity and cost of the system, and has certain significance for the improvement of multispectral image acquisition technology.

Error bounds of Lanczos approach for trust-region subproblem

Because of its vital role of the trust-region subproblem （TRS） in various applications, for example, in optimization and in ill-posed problems, there are several factorization-free algorithms for solving the large-scale sparse TRS. The truncated Lanczos approach proposed by N. I. M. Gould, S. Lucidi, M. Roma, and P. L. Toint [SIAM J. Optim., 1999, 9： 504-525] is a natural extension of the classical Lanczos method for the symmetric linear system and eigenvalue problem and, indeed follows the classical Rayleigh-Ritz procedure for eigenvalue computations. It consists of 1） projecting the original TRS to the Krylov subspa^es to yield smaller size TRS＇s and then 2） solving the resulted TRS＇s to get the approximates of the original TRS. This paper presents a posterior error bounds for both the global optimal value and the optimal solution between the original TRS and their projected counterparts. Our error bounds mainly rely on the factors from the Lanczos process as well as the data of the original TRS and, could be helpful in designing certain stopping criteria for the truncated Lanczos approach.