Efficient Achromatic Broadband Focusing and Polarization Manipulation of a Novel Designed Multifunctional Metasurface Zone Plate

In this paper, comprehensively utilizing the diffraction theory and electromagnetic resonance effect is creatively employed to design a multifunctional metasurface zone plate (MMZP) and achieve the control of polarization states, while maintaining a broadband achromatic converging property in a near-IR region. The MMZP consists of several rings with fixed width and varying heights; each ring has a number of nanofins (usually called meta-atoms). The numerical simulation method is used to analyze the intensity distribution and polarization state of the emergent light, and the results show that the designed MMZP can realize the polarization manipulation while keeping the broadband in focus. For a specific design wavelength (0.7μm), the incident light can be converted from left circularly polarized light to right circularly polarized light after passing through the MMZP, and the focusing efficiency reaches above 35%, which is more than twice as much as reported in the literature. Moreover, the achromatic broadband focusing property of the MMZP is independent with the polarization state of the incident light. This approach broadens degrees of freedom in micro-nano optical design, and is expected to find applications in multifunctional focusing devices and polarization imaging.

A modified multiplexed vortex helico-conical petal-like zone plate

A modified multiplexed vortex helico-conical petal-like zone plate (MMVHPZP) is proposed to generate a polygon-like beam or light-arm beam with an adjustable opening. The MMVHPZP consists of the modified helico-conical petal-like zone plate (MHPZP) with the topological charge l and exponent n, and the multiplexed vortex spiral phase plate (MVSPP) with the inner topological charge l1 and outer topological charge l2. Moreover, when l1 is equal or unequal to l2, the MMVHPZP has the adjustable polygon-like beam or light-arm beam, respectively. In addition, when n is small or large, the number of arms is equal to the absolute difference between l1 and l2 or the sum of one and the absolute difference between l1 and l2, respectively. Furthermore, for the different l1 or l2, the opening is constant. With the increase of the n or l, the opening is larger. When l1 is greater or less than l2, the rotation direction of arms is the anticlockwise or clockwise direction, respectively.

Phase-Type Fresnel Zone Plate with Multi-Wavelength Imaging Embedded in Fluoroaluminate Glass Fabricated via Ultraviolet Femtosecond Laser Lithography

Herein, we report a novel optical glass material, fluoroaluminate (AlF3) glass, with excellent optical transmittance from ultraviolet to infrared wavelength ranges, which provides more options for application in optical devices. Based on its performance, the phase-type Fresnel zone plate (FZP) by ultraviolet femtosecond (fs) laser-inscribed lithography is achieved, which induces the refractive index change by fs-laser tailoring. The realization of ultraviolet fs-laser fabrication inside glass can benefit from the excellent optical performance of the AlF3 glass. Compared with traditional surface-etching micro-optical elements, the phase-type FZP based on AlF3 glass exhibits a clear and well-defined geometry and presents perfect environmental suitability without surface roughness problems. Additionally, optical focusing and multi-wavelength imaging can be easily obtained. Phase-type FZP embedded in AlF3 glass has great potential applications in the imaging and focusing in glass-integrated photonics, especially for the ultraviolet wavelength range.