###### Abstract  
The use of array generators has become ubiquitous in various applications such as laser fabrication, face identification, and motion sensing. The Dammann grating, a diffractive optical element, is the mainstream approach for generating uniform spot arrays. However, its limited capability and the contradiction between the performance and the complexity of fabrication hinder its application. To address this issue, an all-in-one collimating splitter based on metasurfaces is theoretically proposed by synthesizing the phase of an inverse-optimized Dammann grating and a collimating lens. Leveraging both the diffraction effect of Dammann grating and the Fourier transformation of the collimating lens, the number of spot arrays can be largely increased with a single lenslet. The proposed design shows a large field of view of \(62^{\circ}\times 62^{\circ}\) and a high uniformity of 1.29% in generating a spot array of \(3\times 3\) on a single-fiber platform, confirmed by both the scalar and full-wave simulation. Further, a larger spot array up to \(15\times 15\) is also derived in the far field by integrating the proposed metasurface on a \(5\times 5\) fiber array platform, confirmed by the scalar simulation. Our design may be transplanted to the vertical-cavity surface-emitting laser platform, and shows great potential in various applications including face identification and motion sensing. m 2023 by the authors. Liconse MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license ([[https://creativecommons.org/licenses/py/4.0/](https://creativecommons.org/licenses/py/4.0/)]([https://creativecommons.org/licenses/py/4.0/](https://creativecommons.org/licenses/py/4.0/))). **Key words:** metaferjer array; Dammann grating; spot array generator; collimating splitter; dielectric metasurface  
**1. Introduction**  
Array generators were proposed in the last century for use in laser fabrication to improve the efficiency of this process [1]. With the development of smart devices, the array generator has found new applications in depth sensing for face identification and motion sensing [2, 3]. In a typical spot array generation architecture, light from a laser source is initially collimated by a lens and then directed to a diffractive optical element (DOE), which duplicates the light into a large array across a wide field of view [4]. The most common and efficient approach for generating such a DOE spot array is through the use of Dammann grating. In 1971, [PERSON] introduced a binary-phase grating. By precisely selecting the abrupt phase change points, the phase and amplitude of the spot array in the far-field can be uniformly distributed across different diffraction orders [1]. However, using a binary phase for complex designs is inefficient. Therefore, multilevel-phase gratings were then introduced to improve the diffraction efficiency of the DOE [5]. Nonetheless, as the desired number of spot arrays increases, the design becomes more intricate, which directly lowers the final efficiency and significantly increases the fabrication complexity. Furthermore, the separated configuration of the collimating lens and the DOE is cumbersome and limits its application in smart devices, such as phones. Compared to conventional DOEs, a metasurface consists of planar subwavelength structures, which usually induce local resonance [6, 7]. This attribute confers great flexibility for manipulating the amplitude, phase and polarization of the light waves [8]. Inaddition, the fabrication of the planar nanostructures of the metasurfaces enjoys good CMOS compatibility, which is much simpler than the multilevel DOE fabrication process. Thanks to the flexibility in manipulating light and the good CMOS compatibility in terms of fabrication, various applications of metasurfaces have been demonstrated, including imaging [9; 10; 11; 12], holography [13; 14; 15; 16], beam steering [17; 18; 19; 20; 21; 22], beam shaping [23; 24] and so on.