# _Photonics_
## 1 Introduction  
Polarization is a significant feature of electromagnetic (EM) waves. It is crucial in a number of useful applications such as the optical switching of visible light polarization [1], antenna for radar and communication systems [2], satellite communication [3], RCS reduction [4], and many more. The polarization of EM waves is defined as the direction of the oscillation of the electric field in a perpendicular plane with respect to the direction of propagation [5]. The polarization state of EM waves should be effectively controlled and manipulated as it is extremely covered for because many riveting phenomena are deeply vulnerable to polarization [6, 7]. Birefringent materials, namely liquid crystals [8, 9] have traditionally been thought of as techniques to regulate polarization rotation. These materials, on the other hand, have bulky sizes and high insertion losses. Finding creative techniques to manipulate polarization in a highly efficient and convenient manner is in high demand. In this stream, metasurfaces [10, 11, 12, 13, 14], a form of planar periodic subwavelength-sized structure with exceptional EM properties, have gained considerable interest in recent decades. These offer greater flexibility in tailoring and manipulating electromagnetic waves than the bulkier conventional materials. Further, their key benefits are a simple design, low loss, cost-effectiveness, and compact size [15, 16, 17]. Metasurfaces have shown tremendous potential in light field manipulation, offering precise control over the amplitude,phase, and polarization of light at subwavelength scales. As highlighted in the literature, such as [18; 19; 20; 21; 22], metasurfaces enable advanced applications, including wavefront shaping, holography, and beam steering. These capabilities are crucial for developing compact and efficient optical devices, such as lenses, modulators, and sensors, which can be tailored for wideband operation. In this context, there are two configurations for polarization conversion, one is reflection mode and the other is transmission mode. In the transmission mode, the polarization converters found are of two types. One is based on the chiral metamaterials and their optical activity, and on the other hand, the birefringence effect shown by the anisotropic meta-materials forms the basis of the second one [23; 24; 25; 26; 27; 28; 29]. It is investigated that neither approach can achieve wide bandwidth and better efficiency consequently. Using metasurfaces, the polarization conversion is achieved for dualband [30], multiband [31], and broadband [32; 33]. Several investigations have been published for expanding the bandwidth of the polarization conversion; these include ring/disk cavity structures [34], double V-shaped patches [35], double U-shaped MMs [36], and cut-wire structures [37]. Several works [38; 39; 40] present innovative approaches to polarization control through dynamic metasurfaces, offering valuable insights into design strategies. Nevertheless, most are unable to achieve wide-angle, ultra-broadband, and greatly increased efficiency, as well as simple geometry at the same time. Another technique for achieving reflective polarization conversion is topology design based on symmetry coding [41]. However, at several operating band frequencies, the polarization conversion ratio (PCR) is less than 90%. Recent advancements in multi-layer metasurfaces have significantly expanded the capabilities of optical devices. [PERSON] et al. demonstrated the potential of multi-layer metasurfaces to achieve precise control over light's phase, amplitude, and polarization, enabling complex functionalities beyond the reach of single-layer designs [42]. Similarly, [PERSON] et al. introduced composite metasurfaces for multispectral achromatic optics, effectively correcting chromatic aberrations across a wide range of wavelengths [43]. [PERSON] et al. further explored innovative multi-layer metasurface designs that provide high-efficiency beam shaping and focusing across broad spectral ranges [44].