Ultra-robust informational metasurfaces based on spatial coherence structures engineering

Optical information transmission is vital in modern optics and photonics due to its concurrent and multi-dimensional nature,leading to tremendous applications such as optical microscopy,holography,and optical sensing.Conventional optical information transmission technologies suffer from bulky optical setup and information loss/crosstalk when meeting scatterers or obstacles in the light path.Here,we theoretically propose and experimentally realize the simultaneous manipulation of the coherence lengths and coherence structures of the light beams with the disordered metasurfaces.The ultra-robust optical information transmission and self-reconstruction can be realized by the generated partially coherent beam with modulated coherence structure even 93%of light is recklessly obstructed during light transmission,which brings new light to robust optical information transmission with a single metasurface.Our method provides a generic principle for the generalized coherence manipulation on the photonic platform and displays a variety of functionalities advancing capabilities in optical information transmission such as meta-holography and imaging in disordered and perturbative media.

Enhanced second-harmonic generation from two-dimensional MoSe_(2) on a silicon waveguide

Two-dimensional transition-metal dichalcogenides(TMDCs)with intrinsically broken crystal inversion symmetry and large secondorder nonlinear responses have shown great promise for future nonlinear light sources.However,the sub-nanometer monolayer thickness of such materials limits the length of their nonlinear interaction with light.Here,we experimentally demonstrate the enhancement of the second-harmonic generation from monolayer MoSe_(2) by its integration onto a 220-nm-thick silicon waveguide.Such on-chip integration allows for a marked increase in the interaction length between the MoSe_(2) and the waveguide mode,further enabling phase matching of the nonlinear process.The demonstrated TMDC–silicon photonic hybrid integration opens the door to second-order nonlinear effects within the silicon photonic platform,including efficient frequency conversion,parametric amplification and the generation of entangled photon pairs.

Metasurface doublet-integrated bidirectional grating antenna enabling enhanced wavelength-tuned beam steering

We propose and demonstrate an optical phased-array-based bidirectional grating antenna(BDGA) in silicon nitride waveguides.The BDGA is integrated with a miniaturized all-dielectric metasurface doublet(MD) formed on a glass substrate.The BDGA device,which takes advantage of alternately feeding light to its ports in opposite directions,is presumed to effectively provide a doubled wavelength-tuned steering efficiency compared to its unidirectional counterpart.The MD,which is based on vertically cascaded convex and concave metalenses comprising circular hydrogenated amorphous silicon nanopillars,is meticulously placed atop the BDGA chip to accept and deflect a beam emanating from the emission area,thereby boosting the beam-steering performance.The manufactured BDGA could achieve an enhanced beam-steering efficiency of 0.148 deg/nm as well as a stable spectral emission response in the wavelength range of 1530–1600 nm.By deploying a fabricated MD atop the silicon photonic BDGA chip,the steering efficiency was confirmed to be boosted by a factor of ~3.1,reaching 0.461 deg/nm,as intended.

Angle tolerant transmissive color filters exploiting metasurface incorporating hydrogenated amorphous silicon nanopillars

Angle tolerant transmissive subtractive color filters incorporating a metasurface exploiting hydrogenated amorphous silicon nanopillars(NPs) on a glass substrate were proposed and demonstrated. The achieved transmission efficiency ranged from 75% to 95% at off-resonance wavelengths. For an NP resonator, electric and magnetic-field distributions in conjunction with absorption cross-sections were investigated to confirm a resonant transmission dip, which is primarily governed by the absorption resulting from simultaneous excitation of magnetic and electric dipoles via Mie scattering. The proposed devices exhibit higher angular tolerance and lower crosstalk for the absorption spectra and, therefore, are applicable with photodetectors, image sensors, and imaging/display devices.