Third Harmonic Generation Enhancement and Wavefront Control Using a Local High-Q Metasurface

Creators: Hail, Claudio U.; Michaeli, Lior; Atwater, Harry A.¹

1. California Institute of Technology

Abstract

High quality factor optical nanostructures provide a great opportunity to enhance nonlinear optical processes such as third harmonic generation. However, the field enhancement in these high quality factor structures is typically accompanied by optical mode nonlocality. As a result, the enhancement of nonlinear processes comes at the cost of their local control as needed for nonlinear wavefront shaping, imaging, and holography. Here we show simultaneous strong enhancement and spatial control over third harmonic generation with a local high-Q metasurface relying on higher-order Mie resonant modes. Our results demonstrate third harmonic generation at an efficiency of up to 3.25 × 10^–5, high quality wavefront shaping as illustrated by a third harmonic metalens, and a flatband, angle independent, third harmonic response up to ±11° incident angle. The demonstrated high level of local control and efficient frequency conversion offer promising prospects for realizing novel nonlinear optical devices.

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Acknowledgement

This work was supported by the Air Force Office of Scientific Research under Grant FA9550-18-1-0354 and the Meta-Imaging MURI Grant #FA9550-21-1-0312. C.U.H. also acknowledges support from the Swiss National Science Foundation through the Early Postdoc Mobility Fellowship Grant #P2EZP2_191880 and the Postdoc Mobility Grant #P500PT_214452. L.M. acknowledges support from the Fulbright Fellowship program and the Breakthrough Foundation. We gratefully acknowledge the critical support and infrastructure provided for this work by The Kavli Nanoscience Institute at Caltech.

Contributions

C.U.H., L.M., and H.A.A. conceived the project. C.U.H. preformed the simulations, fabricated the devices, built the experiment, performed the measurements, and analyzed the results. L.M. assisted in experiment design, simulations, and data analysis and interpretation. C.U.H. wrote the manuscript with input from all other authors. H.A.A. supervised all aspects of the project.

Conflict of Interest

The authors declare no competing financial interest.

Data Availability

Multipole expansion of the reflected field amplitude, angular dispersion of the metasurface, measured pump spectra, TH phase look-up table, experimental setup, refractive index of amorphous silicon, comparison to the state of the art, metalens design parameters, methods, derivation of the TH power as a function of NA, calculation of the effective third-order nonlinear susceptibility (PDF)

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