“Lab‐on‐fiber” technology, which combines the unique merits of optical fibers with nanophotonic platforms, has received significant investigation due to its profound ability to control light at the nanoscale, which has significantly boosted the functionalities of conventional fibers. Previous plasmonic‐based fiber meta‐tips (FMTs) have been inhibited by the intrinsic ohmic losses of the metallic structures, resulting in limited light manipulation efficiency. In addition, to become prominent candidates for integrated photonics, their functional diversity needs to be enhanced. In this study, an FMT constructed by tethering an all‐dielectric metasurface to a single‐mode fiber for bifunctional light manipulation is implemented. Distinct light manipulation, including vortex generation and beam collimation, is executed by tailoring the phase profiles encoded in the metasurface for transverse electric and transverse magnetic polarized light. To build the proposed FMT, a polarization‐selective metasurface is first created via lithography nanofabrication and then attached to an optical fiber with the aid of a vision system. Moreover, as a proof‐of‐concept, the feasibility of exploiting the established FMT for applications such as optical interconnects is demonstrated. The resulting fiber optics and metasurface‐based meta‐tip represent a major breakthrough in the lab‐on‐fiber technology roadmap for applications such as optical communication, optical trapping, and biological sensing.

networks, [1] augmented/mixed reality, [2] optical sensors, [3] and laser tracking. [4] For free-space optical communications in the case of wireless data transfer between mobile (e.g., aircrafts, ships, and satellites) and stationary terminals, both passive and active modulating retroreflectors have been extensively investigated. [5][6][7][8][9] The wavefront pertaining to geometrical optical devices is mediated by the accumulated phase shift over a relatively long propagation distance. [10,11] Therefore, conventional retroreflectors such as cat's eye and corner-cube types are particularly subject to shortcomings in terms of their bulky size, heavy weight, and nonplanar shape.Metasurfaces, incorporating specifically engineered subwavelength nanostructures, have been prevalently leveraged to tailor the phase, amplitude, polarization, and spectrum of light beams. [12][13][14] Metasurface-based devices based on nanoresonators allow for dispersion characteristics that are dictated mainly by the geometrical parameters and structural arrangement, and they facilitate facile wavefront manipulations unlike conventional geometrical optics-based components. [15][16][17][18][19] Recently, flat retroreflectors (FRRs) based on a singlet metasurface were proposed, providing merits with respect to their miniaturization and integration with other optic/electronic devices. [20,21] However, their limited angles of operation may constitute a concern to be solved. [22] To mitigate this, metasurface doublets (MDs), which are geared to render successive beam manipulations, have been actively studied. [23][24][25][26][27] For example, an MD-based retroreflector that render wide-angle retroreflections at a wavelength of 850 nm was proposed. [25] Compared with an 850-nm wavelength, which is mostly used for imaging and biometrics, [28] a 1550-nm wavelength in the C-band is unequivocally desirable for long-distance optical communications from the perspective of its minimal attenuation in optical fibers, good eye safety, and compatibility with an erbium-doped fiber amplifier (EDFA). [29][30][31] To the best of our knowledge, there has been no report on the demonstration of a metasurface-based retroreflector for implementing free-space optical communications.In this paper, a reliable and highly angle tolerant optical link capitalizing on an MD-based FRR is proposed and demonstrated to operate in the telecommunications regime centered at λ = 1550 nm. The proposed MD incorporates arrayed hydrogenated

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