Efficient Frequency Conversion with Geometric Phase Control in Optical Metasurfaces

Year: 2022

Authors: Reineke Matsudo B.; Sain B.; Carletti L.; Zhang X.; Gao W.; de Angelis C.; Huang L.; Zentgraf T.

Autors Affiliation: Department of Physics, Paderborn University, Warburger StraYAe 100, Paderborn, 33098, Germany; Department of Information Engineering and National Institute of Optics (CNR-INO), University of Brescia, Brescia, 25123, Italy; School of Optics and Photonics, Beijing Institute of Technology, Beijing, 100081, China

Abstract: Metasurfaces have appeared as a versatile platform for miniaturized functional nonlinear optics due to their design freedom in tailoring wavefronts. The key factor that limits its application in functional devices is the low conversion efficiency. Recently, dielectric metasurfaces governed by either high-quality factor modes (quasi-bound states in the continuum) or Mie modes, enabling strong light-matter interaction, have become a prolific route to achieve high nonlinear efficiency. Here, an effective way of spatial nonlinear phase control by using the Pancharatnam-Berry phase principle with a high third harmonic conversion efficiency of 10(-4) W-2 is demonstrated both numerically and experimentally. It is found that the magnetic Mie resonance appears to be the main contributor to the third harmonic response, while the contribution from the quasi-bound states in the continuum is negligible. This is confirmed by a phenomenological model based on coupled anharmonic oscillators. Besides, the metasurface provides experimentally a high diffraction efficiency (80%-90%) in both polarization channels. A functional application of this approach is shown by experimentally reconstructing an encoded polarization-multiplexed vortex beam array with different topological charges at the third harmonic frequency with high fidelity. The approach has the potential viability for future on-chip nonlinear signal processing and wavefront control.


Volume: 9 (12)      Pages from: 2104508-1  to: 2104508-12

More Information: This project received funding from the European Research Council (ERC) under the European Union´s Horizon 2020 research and innovation programme (Grant Agreement No. 724306) and the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) -SFBGeschaftszeichen TRR142/2-2020 -Projektnummer 231447078 -Teilprojekt C05. The authors also acknowledge the NSFC-DFG joint program (DFG No. ZE953/11-1, NSFC No. 61861136010) for continuous support.
KeyWords: bound states in the continuum; harmonic generation; metasurfaces; nonlinear optics; nonlinear vortex beams; Pancharatnam-Berry phase; phase control
DOI: 10.1002/advs.202104508