Dielectric Broadband Metasurfaces for Fiber Mode‐Multiplexed Communications

Abstract

nanophotonic structures [1] avoid absorption losses which drastically enhances the overall performance, [3][4][5][6][7][8][9] especially in the transmission regime. Recently, all-dielectric metasurfaces have reached remarkable efficiencies, often matching or outperforming conventional optical elements. [1] Here, we suggest to broaden the application range of metasurfaces and employ them for mode multiplexing and dynamic control in fiber optics, offering near lossless transmission within the telecom C-and L-bands, [4] which will make metasurfaces a promising technology for mode multiplexers and other applications in optical communications.Optical fiber communications is a key enabling technology in our modern information-centric society. In the past decades, there has been a significant increase in the amount of data transmitted through a fiber, [10] which has been possible by multiplexing light across the physical dimensions of time, wavelength, polarization, and quadratures (amplitude and phase). However, the data rates of existing technologies are rapidly approaching the Shannon limit. [11] To surpass this limit, considerable attention has been given to multiplexing data over the last physical dimension: space. [11][12][13][14] This technology, known as space-division multiplexing, can increase the throughput by transmitting data over individual cores of multicore fibers, [15] and/or orthogonal spatial modes of few-mode or multimode fibers (MMFs). [16,17] With these techniques, a two-order increase in the throughput is achievable compared to a single-mode fiber (SMF). [18] Among the space-division multiplexing approaches, multiplexing data onto orthogonal spatial modes, known as mode-division multiplexing (MDM), has the biggest potential for further scaling down cost-per-bit and energy-per-bit of information transfer. Meanwhile, implementation of MDM requires efficient mode multiplexers and demultiplexers. So far, holographic excitation with spatial light modulators (SLMs), [19] photonic lanterns, [20] integrated devices, [21] and free-space multiplane light conversion, [22] are among the demonstrated techniques for mode multiplexing/demultiplexing. However, there exists a common issue with the currently developed techniques: it is not possible to simultaneously convert each of the two orthogonal polarizations of an input beam to two individual higher-order modes without using some polarization diversity setup, which increases losses and sensitivity to alignment tolerances. Independent conversion of two polarization-multiplexed fundamental modes A subwavelength-thick spatial-mode multiplexer based on a highly transparent all-dielectric Mie-resonant metasurface is demonstrated with a broadband response covering major optical communication wavelength bands. The metasurface is employed to convert simultaneously each orthogonal polarization of LP 01 inputs into individual higher-order TM 01 and TE 01 vectorial modes, without the need of a polarization diversity setup. This is not feasible using current mode multipl...

Efficient Optical Angular Momentum Manipulation for Compact Multiplexing and Demultiplexing Using a Dielectric Metasurface

“…Though these methods have successfully realized the AM multiplexing/demultiplexing on the nanodevice, the inevitable Ohmic loss of the metallic nanostructures results in low efficiency of the proposed systems. The dielectric metasurface, expanding an excellent performance for manipulation of electromagnetic wave with a high efficiency, has also been used to explore light multiplexing/demultiplexing 41–44. The angle‐multiplexed metasurface, composed of dielectric U‐shaped meta‐atoms, is proposed by S.M.…”

Metalens-integrated compact imaging devices for wide-field microscopy

“…Benefiting from the development of nanofabrication technology, the metasurface as a new breakthrough of optical design has demonstrated tremendous capabilities in manipulating light by subwavelength unit cells, [9][10][11][12] and fascinating applications with the low loss dielectric metasurfaces have been revealed. [13][14][15][16] Among these applications, the metalens is one of the most promising candidates for upgrading current optical systems. During the past several years, exciting progress concerning the imaging performance of the metalens has been made, including improved efficiency, 17,18 broadband achromaticism, [19][20][21] broadened field-of-view (FOV), 22,23 polarization functionalities, 24,25 etc., which indicates a closer step toward real applications.…”

Time-varying optical vortices enabled by time-modulated metasurfaces

“…Moreover, metasurface-based optical components yield a great potential for enabling novel functionalities and/or outperforming their conventional bulky counterparts in terms of efficiency. Owing to the remarkable advantages offered by metasurfaces, they have been widely used as a mean of generating OAM-carrying light beams for different purposes including optical communication [39][40][41]. However, despite these expeditious growths in metasurface-based concepts both in theoretical and practical aspects, a main drawback of static metasurfaces is their fixed functionality.…”