An optical metamixer

TL;DR

This paper demonstrates an optical frequency mixer using a GaAs-based dielectric metasurface that generates eleven new frequencies across ultraviolet to near-infrared, leveraging strong nonlinearities and relaxed phase-matching conditions.

Contribution

It introduces a versatile optical mixer that combines multiple nonlinear processes simultaneously using a metasurface, overcoming traditional phase-matching limitations.

Findings

Generated eleven new frequencies from ultraviolet to NIR.

Observed seven different nonlinear optical processes simultaneously.

Achieved ultracompact optical mixing suitable for diverse applications.

Abstract

A frequency mixer is a nonlinear device that combines electromagnetic waves to create waves at new frequencies. Mixers are ubiquitous components in modern radio-frequency technology and are widely used in microwave signal processing. The development of versatile frequency mixers for optical frequencies remains challenging: such devices generally rely on weak nonlinear optical processes and, thus, must satisfy phase matching conditions. In this work, we utilize a GaAs-based dielectric metasurface to demonstrate an optical frequency mixer that concurrently generates eleven new frequencies spanning the ultraviolet to near-infrared (NIR) spectral range. Our approach combines strong intrinsic material nonlinearities, enhanced electromagnetic fields, and relaxed phase-matching requirements, to allow seven different nonlinear optical processes to occur simultaneously. Specifically, when pumped by two femtosecond NIR pulses, we observe second-, third- and fourth-harmonic generation, sum-frequency generation, two-photon absorption induced photoluminescence, four-wave mixing, and six-wave mixing. Such ultracompact optical mixers may enable a plethora of applications in biology, chemistry, sensing, communications and quantum optics.