Identity Authentication Based on Two-Beam Interference

A two-factor identity authentication method on the basis of two-beam interference was presented. While verifying a user’s identity, a specific “phase key” as well as a corresponding “phase lock” are both mandatory required for a successful authentication. Note that this scheme can not only check the legality of the users, but also verify their identity levels so as to grant them hierarchical access permissions to various resources of the protected systems or organizations. The authentication process is straightforward and could be implemented by a hybrid optic-electrical system. However, the system designing procedure involves an iterative Modified Phase Retrieval Algorithm (MPRA) and can only be achieved by digital means. Theoretical analysis and simulations both validate the effectiveness of our method.

Large-area straight,regular periodic surface structures produced on fused silica by the interference of two femtosecond laser beams through cylindrical lens

Inhomogeneity and low efficiency are two important factors that limit the application of laser-induced periodic surface structures(LIPSSs),especially on glass surfaces.In this study,two-beam interference(TBI)of femtosecond lasers was used to produce large-area straight LIPSSs on fused silica using cylindrical lenses.Compared with those produced us-ing a single circular or cylindrical lens,the LIPSSs produced by TBI are much straighter and more regular.Depending on the laser fluence and scanning velocity,LIPSSs with grating-like or spaced LIPSSs are produced on the fused silica sur-face.Their structural colors are blue,green,and red,and only green and red,respectively.Grating-like LIPSS patterns oriented in different directions are obtained and exhibit bright and vivid colors,indicating potential applications in surface coloring and anti-counterfeiting logos.

Laser interference fabrication of large-area functional periodic structure surface

Functional periodic structures have attracted significant interest due to their natural capabilities in regulating surface energy, surface effective refractive index, and diffraction. Several technologies are used for the fabrication of these functional structures. The laser interference technique in particular has received attention because of its simplicity, low cost, and high-efficiency fabrication of large-area, micro/nanometer-scale, and periodically patterned structures in air conditions. Here, we reviewed the work on laser interference fabrication of large-area functional periodic structures for antireflection, self-cleaning, and superhydrophobicity based on our past and current research. For the common cases, four-beam interference and multi-exposure of two-beam interference were emphasized for their setup, structure diversity, and various applications for antireflection, self-cleaning, and superhydrophobicity. The relations between multi-beam interference and multi-exposure of two-beam interference were compared theoretically and experimentally. Nanostructures as a template for growing nanocrystals were also shown to present future possible applications in surface chemical control. Perspectives on future directions and applications for laser interference were presented.

Regular uniform large-area subwavelength nanogratings fabricated by the interference of two femtosecond laser beams via cylindrical lens

Inhomogeneity and low efficiency are two important factors that hinder the wide application of laser-induced periodic surface structures. Two-beam interference is commonly used to fabricate gratings with interference periods. This study reports regular and uniform periodic ripples fabricated efficiently by the interference of two femtosecond laser beams via a cylindrical lens. The interference period is adjusted to be an integer multiple of the wavelength of a surface plasmon polariton. Regular and uniform subwavelength nanogratings(RUSNGs)on a silicon wafer of a diameter of 100 mm are fabricated with a scanning velocity of 6–9 mm/s. Bright and pure colors(including purple, blue, and red) are demonstrated on different patterns covered with RUSNGs.