Wei Zhang

Single-layer metalenses are constrained by the dispersion of their meta-atoms, posing a significant challenge to simultaneously achieve polarization-insensitive, wide field-of-view (FOV), and achromatic imaging in the visible. Here, we propose a polarization-insensitive wide-FOV achromatic metalens based on complex topological meta-atoms. We construct a library of rotationally symmetric structures providing continuous phase coverage and high group delays. A multi-objective dynamic-weight particle swarm optimization algorithm is developed to synergistically optimize the phase profile at a reference wavelength and the group delay distribution, enabling wide-FOV phase matching across the visible band. Simulation results demonstrate achromatic and wide-FOV focusing exceeding 50° over 400-750 nm with a numerical aperture of 0.29 and average focusing efficiency > 40%. This work offers a viable route toward high-performance planar integrated imaging systems.

Circular Airy beams exhibit self-healing, non-diffracting properties for enhanced environmental resistance, and autofocusing capability. However, the peak power achievable from a single circular Airy beam remains insufficient for applications such as superhard material processing or high-energy laser confrontation. This paper proposes a method to multiplex circular Airy beams, which could enhance the light intensity at the position of focus. A metasurface is elaborately designed to integrats grating phase, circular Airy beam phase and achromatic compensation phase, which would regulates incident plane waves with the specific combination of oblique angle and wavelength to form a overlapping circular Airy beams with the same focal length in the output space. The focal length of the metasurface is 60 μ m, which could cover a working wavelength range of 450–600 nm, as well as an off-axis angle range of 26.7°–36.8° (with the grating period of 1 μ m) and 13°–17.4° (with the grating period of 2 μ m). When five circular Airy beams are multiplexed, the intensity of the overlapping output beam can be 9.1 times higher than that of a single beam. This work provides a new approach for generating high-power circular Airy beams, promising significant potential in laser confrontation and laser processing applications.

Blazed gratings are widely employed in polarization spectral imaging technology. This work systematically investigates the polarization mechanisms of low blaze angle ruled gratings in the -1st order Littrow mounting and fabricated high-efficiency polarization-independent low blaze angle ruled grating samples. We conducted a study through rigorous coupled-wave analysis (RCWA), the Drude–Lorentz dispersion model for aluminum (Al), and experimental validation. Simulation results show that a grating of 600 gr/mm groove density and a blaze angle of 2° achieves TE and TM efficiencies above 80%, and a polarization degree (PD) value under 0.6% at a wavelength of 116 nm, a low blaze angle plays a dominant role in suppressing PD. The simulated TE and TM efficiencies and PD of grating samples show good agreement with measurements in the 260–1000 nm range, validating the modeling approach and enabling reliable prediction that at its blaze wavelength of 123 nm, Grating–IV maintains TE and TM efficiencies above 85% with an extremely low PD of about 0.16%. Simulations and experiments confirm that the high groove density and low blaze angle gratings in the −1st order Littrow mounting achieve both high diffraction efficiency and polarization independence, providing practical guidance for grating design.

Complete 2π cycling of a phase around a phase singularity leads to a rapid phase variation in the nearby zones and forms a sharp local k-vector peak. In this paper, the intensity distribution in the spatial domain is transformed into a k-vector distribution in the wave vector domain, and we prove that the local k-vector peak is generated at the point of minimum light field intensity. The local k-vector peak is sharper when the minimum point is closer to the phase singularity. The k-vector peak can be manipulated by controlling the minimum optical field intensity. A metalens is designed to generate sharp k-vector peaks for continuous wavelengths and linearly shift the positions of these peaks with the incident wavelength. This method transforms full-band continuous optical spectra from the spatial domain to the wave vector domain. The spectral resolutions over the wavelength range from 800 nm to 810 nm are less than 0.82 nm, and the optimal spectral resolution reaches 0.027 nm. This approach can be used in metasurface spectroscopy, providing what we believe to be a new way to improve spectral resolution.

Scanned reactive‐ion‐beam etching method was proposed to transfer two‐dimensional mask patterns into quartz substrate, which would produce a larger‐size and polarization‐independent two‐dimensional grating. This method was realized by moving grating substrate in a unidimensional scanning manner and adjusting ion beam density in the vertical scanning direction. Graphite plates between the ion beam source and the substrate were used to correct the beam density. The original Gaussian ion beam density was changed to a uniform distribution to establish a knife‐edge shape around the vertical scanning direction. Therefore, a large‐area pattern with consistent depth and duty cycle would be engraved into a quartz substrate. A two‐dimensional, 1200 groves/mm grating with an 85‐mm × 85‐mm area was fabricated under scanned reactive‐ion‐beam etching method and exhibited a 0.197 λ ( λ = 632.8 nm) diffraction wave front. At 780 nm, the efficiency nonuniformity was less than 9%, and the average diffraction efficiencies of transverse‐magnetic and transverse‐electric polarized light were 57.2 and 58.0%, respectively. The large‐size two‐dimensional grating with uniform diffraction efficiency and polarization independence enabled grating displacement measurement with high resolution, long measurement range, multiple degrees of freedom, and potential miniaturization.