Multiplexed Nondiffracting Nonlinear Metasurfaces

Abstract

Metasurfaces and planar photonic nanostructures have drawn great interest from the optical scientific community due to their diverse abilities of manipulating electromagnetic waves and high integration. Most metasurfaces launch diffracting waves, and thus suffer from divergence, short working distance, and instability. Although much effort has been devoted to researching nondiffracting metasurfaces which can launch electromagnetic waves with constant transverse intensity profiles in free‐space propagation, the number of working channels is inherently limited as these meta‐devices are implemented in the linear optical regime. Here, the multiplexed nondiffracting nonlinear metasurfaces are theoretically proposed and experimentally realized, which can generate the representative nondiffracting Bessel beam and Airy beam. Three Bessel beams with different numerical apertures and topological charges and three Airy beams with different propagation curves and focal lengths can be generated by a combination of different spins and wavelengths. The complex properties of the nondiffracting beams can be designed and detected in a more comprehensive and concise way with Fourier analysis. This proof‐of‐concept represents a new strategy for realizing multiplexed nondiffracting metasurfaces with advantages of ultracompactness, high‐pixelation, and easy integration and paves the way for multi‐channel optical communication and manipulation.

Classical and generalized geometric phase in electromagnetic metasurfaces

“…By exploiting the concept of the PB phase in the nonlinear optical regime, many interesting functional devices such as nonlinear lenses [102][103][104] , nonlinear encryption [105] , and nonlinear imaging [106,107] , have been proposed. The multidimensional nonlinear polarization response of nano-material was achieved in a single heterodyne measurement by active manipulation of the polarization states of incident light [108] , and a new kind of metasurface-based THz emitter with the polarization and phase of THz waves finely controlled was demonstrated [109] .…”

Emerging Trend in Unconventional Metasurfaces: From Nonlinear, Non-Hermitian to Nonclassical Metasurfaces

“…The nonlinear geometric phase (NGP) metasurfaces have been employed for various applications in the nonlinear optical regime, such as multiplexed nonlinear holography, 75−78 optical information encoding and encryption, 79,80 control of nonlinear optical spin and orbital angular momentum and nonlinear vortex beam generation, 81−83 generation of nondiffraction harmonic signals, 84 nonlinear metalens and imaging systems, 85,86 integrated THz generation and manipulation, 87,88 full complex amplitude control of harmonic signals, 89 quasicrystal nonlinear metasurfaces, 90 nonlinear optical diffraction, 91 asymmetric optical transport, 92 and others. 93−95 It was shown that the different geometric phases that are involved in the linear and nonlinear optical interactions provide new degrees of freedom for generating wavelength and spin multiplexed information channels.…”

“…The nonlinear geometric phase (NGP) metasurfaces have been employed for various applications in the nonlinear optical regime, such as multiplexed nonlinear holography, − optical information encoding and encryption, , control of nonlinear optical spin and orbital angular momentum and nonlinear vortex beam generation, − generation of nondiffraction harmonic signals, nonlinear metalens and imaging systems, , integrated THz generation and manipulation, , full complex amplitude control of harmonic signals, quasi-crystal nonlinear metasurfaces, nonlinear optical diffraction, asymmetric optical transport, and others. − It was shown that the different geometric phases that are involved in the linear and nonlinear optical interactions provide new degrees of freedom for generating wavelength and spin multiplexed information channels . The nonlinear metasurfaces can also be designed to control the local amplitude by arranging multiple nanostructures of identical shapes but different orientations into each unit cell. , It should be noted that besides NGP metasurfaces, there are also other ways to achieve control of the nonlinearity phase in harmonic generations, such as by tailoring the geometry of each individual nanostructure of the metasurface. − …”

Full Complex‐Amplitude Modulation of Second Harmonic Generation with Nonlinear Metasurfaces

“…The latest advances in metasurfaces revealed their great advantages for nonlinear wave generation and manipulation. [ 31–50 ] The phase‐matching condition in nonlinear process can be significantly relaxed in metasurfaces since their thickness is at the subwavelength scale. Meanwhile, the localized surface plasmonic resonances in metasurfaces can generate strong enhancement of the electromagnetic fields near the nanoparticles and can greatly boost the efficiency of high harmonic generation.…”

“…[44,45] Nonlinear phase-modulated metasurfaces have been used to realize complete control over the propagation of the high harmonic generation. [46][47][48][49][50] However, previous nonlinear phase-modulated metasurfaces suffer from intrinsic noises due to the loss of intensity information, and such phase-only metasurfaces also cannot realize intensity-only applications such as resolution test targets. Simultaneous manipulation of amplitude and phase of the nonlinear optical signals based on metasurface, which is eagerly anticipated by the scientific community, has not been well explored yet.…”