Metasurface-Based Ultrathin Beam Splitter with Variable Split Angle and Power Distribution

Abstract

Metasurfaces are artificial electromagnetic surfaces that consist of subwavelength scatterers in an array configuration, exhibiting exceptional abilities to manipulate electromagnetic waves. Based on the metasurface concept, a novel beam splitter for a single-frequency same-polarization light is proposed in the visible spectrum. Using metal–dielectric–metal (MDM) scattering unit cells, an array of the circular gold nanocylinders with two different diameters is designed and fabricated on the surface which introduces phase discontinuity on the scattering wavefronts. At 240 nm thick, the flat beam splitter can efficiently reflect an incident wave toward two predesigned directions. More importantly, the split angle and power distribution between these two beams can be readily controlled by setting a proper incident angle. Compared to conventional bulky optical components, the ability of this metasurface-based beam splitter would be very desirable in integrated optical systems.

Multifunctional Beam Manipulation at Telecommunication Wavelengths Enabled by an All‐Dielectric Metasurface Doublet

“…Polarizing beam splitters based on metasurfaces are known to serve as integral platforms in the implementation of various polarization optics. [ 57–61 ] The proposed MD is anticipated to act as a planar polarizing beam splitter, mimicking a Rochon prism, which helps decompose and route an arbitrarily polarized beam into two orthogonally polarized beams. The TE‐polarized component remains on the same optical axis as the input, while the TM‐polarized component deviates from it by an angle depending on θ in .…”

Asymmetric Spatial Power Dividers Using Phase–Amplitude Metasurfaces Driven by Huygens Principle

“…In particular, we assume the element pattern function asNevertheless, the mere cosine function of eq 13 closely resembles the element factor of the metasurface particles. 24,37,40 By substituting eq 13 into eq 12, one can readily infer that, to design an ASPD with a desired set of power ratio levels for the emitting beams, the power coefficients should be chosen as…”

“…To investigate the flexibility of the design, we intend to demonstrate another ASPD dividing the scattered power equally ( P sup gen (θ 2 , φ 2 )/ P sup gen (θ 1 , φ 1 ) = 1) into the same two asymmetric pencil beams, a special functionality that the conventional wave-splitting platforms fail to achieve. 24 Referring to the Huygens principle and the general form of the superposition theorem in eq 10, the ASPD structure must be endowed by the superimposed phase–amplitude pattern, b mn , obtained by assuming to expose two differently oriented beams with identical power budgets. As can be seen in Figure 3c,d, the power ratio level of two scattered beams satisfactorily approaches to unity (about 0.99) with the same desired tilt angles.…”

“…Along the direction of evolution in metasurfaces, it is time to fully manipulate the power intensity pattern of the metasurfaces, an appealing functionality that has not been reported yet. We will illustrate that the conventional beam splitters 24−26 generate two/multiple beams with compulsive power ratios dictated by their tilt angles. Access to asymmetric spatial power dividers (ASPD) with full/independent control over the power level carried by each beam/channel, however, can give us a fabulous flexibility and privilege and is highy demanded in different practical applications, such as satellite communications, multiple-target radar systems, and multiple-input multiple-output (MIMO) communication.…”

All-Dielectric Metasurface-Based Quad-Beam Splitter in the Terahertz Regime

“…As for beam-splitting application, most previous metasurfaces are polarization independent [4,35] or single polarization mode dependent [9,28]. In this article, we propose a method to design ultra-thin, polarization-dependent transmission-type all-silicon dielectric terahertz beam splitters.…”