Stokes meta-hologram toward optical cryptography.

Optical cryptography manifests itself a powerful platform for information security, which involves encrypting secret images into visual patterns. Recently, encryption schemes demonstrated on metasurface platform have revolutionized optical cryptography, as the versatile design concept allows for unrestrained creativity. Despite rapid progresses, most efforts focus on the functionalities of cryptography rather than addressing performance issues, such as deep security, information capacity, and reconstruction quality.

Femtosecond laser plasmonic nano-printing metasurfaces for multiple-dimensional manipulation of light fields.

Metasurfaces enable the multidimensional manipulation of light fields in a subwavelength scale. However, the low-cost preparation of large-area metasurfaces is still a challenge. In this Letter, we first, to the best of our knowledge, use the laser plasmonic nano-printing technique to efficiently manufacture metasurfaces with multidimensional manipulation capability.

Metasurface-assisted multidimensional manipulation of a light wave based on spin-decoupled complex amplitude modulation.

Achieving arbitrary manipulation of the fundamental properties of a light wave with a metasurface is highly desirable and has been extensively developed in recent years. However, common approaches are typically targeted to manipulate only one dimension of light wave (amplitude, phase, or polarization), which is not quite sufficient for the acquisition of integrated multifunctional devices. Here, we propose a strategy to design single-layer dielectric metasurfaces that can achieve multidimensional modulation of a light wave.

Poincaré sphere analogue for optical vortex knots.

We propose a Poincaré sphere (PS) analogue for optical vortex knots. The states on the PS analogue represent the light fields containing knotted vortex lines in three-dimensional space. The state changes on the latitude and longitude lines lead to the spatial rotation and scale change of the optical vortex knots, respectively.

Observation of optical vortex knots and links associated with topological charge.

Knots and links, as three-dimensional topologies, have played a fundamental role in many physical fields. Despite knotted vortex loops having been shown to exist in the light field, the three-dimensional configuration of vortex loop is fixed due to their topological robustness, making the fields with different topologies independent of each other. In this work, we established the mapping between the torus knots/links and the integer topological charge of the optical vortex, and demonstrated the change of the intermediate state with fractional charges.

Femtosecond laser-induced spatial-frequency-shifted nanostructures by polarization ellipticity modulation.

We demonstrate a prominent spatial frequency shift (SFS) for the femtosecond laser-induced periodic structures by only changing the polarization ellipticity of the working laser. The nanostructures are fabricated on the surfaces of silicon (Si) and zinc selenide (ZnSe) using elliptically polarized femtosecond laser pulses, with the pulse duration of 35 fs, the central wavelength of 800nm, and the repetition rate of 1kHz. The experimental results show that the red- and blue-shift trends of the SFS are individually represented on silicon and zinc selenide with the increased polarization ellipticity, where low- and high-spatial-frequency nano-ripples are fabricated, respectively.

Full-Color Holographic Display and Encryption with Full-Polarization Degree of Freedom.

Metasurfaces provide a compact and powerful platform for manipulating the fundamental properties of light, and have shown unprecedented capabilities in both optical holographic display and information encryption. For increasing information display/storage capacity, metasurfaces with more polarization manipulation channel and full-color holographic functionality are now an urgent requirement. Here, a minimalist dielectric metasurface with the capability of full-color holography encoded with arbitrary polarization is proposed and experimentally demonstrated.

Accurate and rapid measurement of optical vortex links and knots.

Optical vortices can evolve in light fields, of which the singularity evolution forms dark lines with complex topological structures, knotted or linked. We propose a method to more accurately and rapidly measure the topology of optical vortex fields. To accurately locate the phase singular points, phase measurement based on digital holography and, further, a numerical search algorithm, are utilized.

Auto-transition of vortex- to vector-Airy beams via liquid crystal q-Airy-plates.

We propose the auto-transition of vortex-Airy to vector-Airy beams realized via a liquid crystal q-Airy-plate, whose director distribution is the integration of a q-plate and a polarization Airy mask. The polarization, phase, intensity distributions of the vortex-vector-Airy beams (VVABs) during the transition process and individual trajectories of the vortex beam, vector beam and Airy beam components are both theoretically and experimentally investigated. Interesting findings show that the pair of vortex components firstly experience transverse deflection with a smaller acceleration than the Airy components and then automatically evolve into a vector component propagating in a straight path.

Wavelength-multiplexing surface plasmon holographic microscopy.

Surface plasmon holographic microscopy (SPHM), which combines surface plasmon microscopy with digital holographic microscopy, can be applied for amplitude- and phase-contrast surface plasmon resonance (SPR) imaging. In this paper, we propose an improved SPHM with the wavelength multiplexing technique based on two laser sources and a common-path hologram recording configuration. Through recording and reconstructing the SPR images at two wavelengths simultaneously employing the improved SPHM, tiny variation of dielectric refractive index in near field is quantitatively monitored with an extended measurement range while maintaining the high sensitivity.

Quantitative phase microscopy for cellular dynamics based on transport of intensity equation.

We demonstrate a simple method for quantitative phase imaging of tiny transparent objects such as living cells based on the transport of intensity equation. The experiments are performed using an inverted bright field microscope upgraded with a flipping imaging module, which enables to simultaneously create two laterally separated images with unequal defocus distances. This add-on module does not include any lenses or gratings and is cost-effective and easy-to-alignment.