## 1 Introduction  
The optical vortex (OV), characterized by a donut intensity distribution and a helically structured wavefront, shows a phase evolution in the form of \(e^{i\theta}\), where \(\theta\) is the azimuthal angle and \(l\) is the topological charge. It has aroused significant scientific curiosity since its discovery in 1992 [1] and produced tremendous applications in the field of optical tweezers [2], optical communication [3], quantum entanglement [4], nanotechnology [5], biomedicine [6], on-chip detectors [7], etc. Nevertheless, conventional OV generators, such as spiral phase plates [8], axicon lenses [9], and pitch fork holograms [10], suffer from limited performance, bulky configurations, and difficulty of integration. Therefore, it is of great urgency to seek miniaturized devices for OV generation and detection, and metasurfaces seem a promising candidate. A metasurface, composed of arrays of sub-wavelength nanostructures, is a two-dimensional (2D) analog of metamaterials. It can manipulate the phase, polarization, and amplitude of electromagnetic waves flexibly at the nanoscale, making the integration and planarization of traditional bulky optical devices possible. It has an inspiringly diverse range of applications in areas such as beam steering [11], polarization conversion [12], holography [13; 14], perfect absorption [15], self-accelerating beams [16], flat lenses [17; 18], etc. The metallic reflective metasurface based on gap plasmons can achieve an efficiency of around 80% in the near-infrared and visible ranges [14]. However, most optical devices work in transmission mode. Due to the inherent ohmic losses, the transmissive metallic metasurfaces suffer from low efficiency. However, low-loss dielectric metasurfaces based on magnetic resonance demonstrate large transmittance, illustrating the potential to become a strong competitor of the metallic metasurface. Lead telluride (PbTe)-based metasurfaces [19] and gallium antimonide (GaSb)-based metasurfaces [20] have an efficiency of over 70% in the mid-infrared range, and silicon (Si) metasurfaces [21] achieve an efficiency of around 90% in the near-infrared range. Moreover, dielectric materials such as titanium dioxide (TiO\({}_{2}\)) [22], gallium nitride (GaN) [23], silicon nitride (Si\({}_{3}\)N\({}_{4}\)) [24], and other high-refractive-index, low-loss materials have also illustrated remarkable performance, with over 70% efficiency in the visible range. However, the materials discussed above render relatively low transmission efficiency in the ultraviolet (UV) range. Furthermore, UV-transparent materials such as CaF\({}_{2}\), MgF\({}_{2}\), and SiO\({}_{2}\) have relatively low refractive indices, making design and fabrication significantly challenging. [PERSON] experimentally demonstrated all-silicon-based broadband UV metasurfaces operating efficiently at wavelengths down to 290 nm. Nonetheless, the device suffered from a low efficiency of under 30% [25]. [PERSON] illustrated a high-performance, complementary metal oxide semiconductor (CMOS) compatible hafnium oxide (HfO\({}_{2}\))-based metasurface working at wavelengths down to a record short deep-UV range [26]. Nevertheless, the aspect ratio of the nanobar was larger than 10, thus adding strict requirements for preparation. [PERSON] designed aluminum nitride (AlN)-based multi-plane meta-holography by adopting circular posts with different diameters at an efficiency of 34.05% [27]. However, the abrupt phase difference formed by the nano-cylinder changed rapidly within a specific range of the cylinder radius, giving little tolerance to manufacturing error. In summary, the ultraviolet metasurface faces three major problems: low efficiency, large aspect ratio, and low fabrication error tolerance. Consequently, we design a niobium pentoxide (Nb\({}_{2}\)O\({}_{5}\))-based transmission-type all-dielectric metasurface to address the challenges discussed above.