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In this study, electromagnetically induced transparency (EIT) effect in all-dielectric metamaterial for dual-band linear-to-circular (LTC) polarization conversion is demonstrated numerically and experimentally. The unit cell is composed of three ceramic blocks with different sizes. Due to the anisotropy of metamaterial and polarization dependence of subsequent EIT effects, transmission spectra for x- and y-polarized incident waves are realized to induce LTC polarization conversion. It is numerically demonstrated that a linearly polarized incident wave is transformed to a nearly perfect circularly polarized wave at around 6.24 and 6.38 GHz. The corresponding ellipticity and transmittivity are about 0.96, 0.6 and 0.94, 0.37, respectively. A metamaterial sample is fabricated and its transmission spectra are measured. The measured results are nearly equal to the simulated results. This LTC polarization convertor, with low loss and ultra thinness, may expand the application of EIT metamaterials, and it can be extended to terahertz up to optical bands. Such a design may find potential applications in microwave wave plates and metamaterial antennas, or other electromagnetic control devices.

We propose simultaneous measurement and reconstruction tailoring (SMaRT) for quantitative phase imaging; it is a joint optimization approach to inverse problems wherein minimizing the expected end-to-end error yields optimal design parameters for both the measurement and reconstruction processes. Using simulated and experimentally-collected data for a specific scenario, we demonstrate that optimizing the design of the two processes together reduces phase reconstruction error over past techniques that consider these two design problems separately. Our results suggest at times surprising design principles, and our approach can potentially inspire improved solution methods for other inverse problems in optics as well as the natural sciences.

We propose a multiple-3D-object decryption scheme based on one interference using two beams that are from two different phase-only functions. It takes advantage of off-axis digital holography to extract the optical fields of multiple 3D objects, and respectively utilize single different decryption keys to decrypt multiple 3D objects in the decryption procedure. The advantages of the proposed scheme include the following: each 3D object can be decrypted discretionarily without decrypting a series of other objects earlier; no iterative algorithm is involved; and the decrypted image of each object can be successfully clearly distinguished. The feasibility of the proposed scheme is verified by the optical holograms of real 3D objects.

We propose a multiple-3D-object secure information system for encrypting multiple three-dimensional (3D) objects based on the three-step phase shifting method. During the decryption procedure, five phase functions (PFs) are decreased to three PFs, in comparison with our previous method, which implies that one cross beam splitter is utilized to implement the single decryption interference. Moreover, the advantages of the proposed scheme also include: each 3D object can be decrypted discretionarily without decrypting a series of other objects earlier; the quality of the decrypted slice image of each object is high according to the correlation coefficient values, none of which is lower than 0.95; no iterative algorithm is involved. The feasibility of the proposed scheme is demonstrated by computer simulation results.

We propose a multiple-image encryption (MIE) scheme based on triple interferences for flexibly decrypting high-quality images. Each image is discretionarily deciphered without decrypting a series of other images earlier. Since it does not involve any cascaded encryption orders, the image can be decrypted flexibly by using the novel method. Computer simulation demonstrated that the proposed method's running time is less than approximately 1/4 that of the previous similar MIE method. Moreover, the decrypted image is perfectly correlated with the original image, and due to many phase functions serving as decryption keys, this method is more secure and robust.