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In this paper, we propose a simple model, a combination of effective medium theory and the Jones matrix, to analyze the optical properties of a dielectric PB-phase metasurface with an arbitrary incident polarization state. The optical properties, such as the polarization conversion efficiency spectrum, rotation-angle-dependent phase modulation, and phasor diagram, shows a fair agreement with the finite difference time domain method results. This model provides a fast and sufficient accuracy compared to the time-consuming finite element methods. Moreover, the shortness of the proposed model is also discussed.

This study presents the design and fabrication of a dielectric metasurface with free-form phase distribution and with a large period unit cell. The dielectric metasurface is fabricated using i-line stepper, dry etching, and nanoimprint technology. The phase distribution of the meta-device is the combination of a blazed grating for deflection and an aspherical lens for eliminating the off-axis aberration. The optical measurement result shows the off-axis focusing spot is with loss aberration and the corresponding Strehl ratio is 0.34. The diffraction efficiency is around 2%. The low efficiency is mainly attributed to the rounding of the rectangular nanostructures during the pattern transfer and relatively thin thickness. Moreover, the polarization-dependency of this large period metasurface is also discussed.

In this study, the phase modulation ability of a dielectric Pancharatnam–Berry (PB) phase metasurface, consisting of nanofins, is theoretically analyzed. It is generally considered that the optical thickness of the unit cell of a PB-phase metasurface is λ/2, i.e., a half-waveplate for polarization conversion. It is found that the λ/2 is not essential for achieving a full 2π modulation. Nevertheless, a λ/2 thickness is still needed for a high polarization conversion efficiency. Moreover, a gradient phase metasurface is designed. With the help of the particle swarm optimization (PSO) method, the wavefront errors of the gradient phase metasurface are reduced by fine-tuning the rotation angle of the nanofins. The diffraction efficiency of the gradient phase metasurface is thus improved from 73.4% to 87.3%. This design rule can be utilized to optimize the efficiency of phase-type meta-devices, such as meta-deflectors and metalenses.

In this paper, the far-field diffraction pattern of a CGH under a reconstruction beam with a beam area smaller than device area of CGH is investigated. A series of beam size is simulated. It is found that the contrast of diffraction pattern will be increased as an increasing area of the reconstruction beam.

In this paper, a miniaturized CPV system is experimentally demonstrated based on a hot embossing silicone lens array with a size of 2 cm × 2 cm. Owing to the small size of the lens array, the total track of the CPV system can be as small as 4 cm. Consquently, the weight of the CPV system can be much lower than conventional bulky CPV system. For harvesting the diffuse solar radiation, perovskite solar cells are mounted adjacent to III-V solar cell. Theoretically, the optical efficiency can be enhanced from 70 % to 76% for γ = 0.7 In the future, we will experimentally integrate III-V solar chip with perovskite solar cell to harvest both direct and diffuse solar light, respectively. The solar conversion efficiency will be discussed as well.