[Paper Review] III-V semiconductor nano-resonators-a new strategy for passive, active, and nonlinear all-dielectric metamaterials

Sheng Liu, Gordon A. Keeler+3 more|ArXiv.org|May 1, 2016

Photonic and Optical Devices7 citations

TL;DR

This paper proposes all-dielectric metamaterials based on epitaxial III-V semiconductor nano-resonators, leveraging high nonlinear susceptibility and monolithic integration of gain media. Using selective wet oxidation to create low-index AlGaO cladding layers in GaAs, the authors demonstrate broadband, near-100% reflectivity in multilayer arrays, enabling passive, active, and nonlinear all-dielectric devices with enhanced functionality.

ABSTRACT

Metamaterials comprising assemblies of dielectric resonators have attracted much attention due to their low intrinsic loss and isotropic optical response. In particular, metasurfaces made from silicon dielectric resonators have shown desirable behaviors such as efficient nonlinear optical conversion, spectral filtering and advanced wave-front engineering. To further explore the potential of dielectric metamaterials, we present all-dielectric metamaterials fabricated from epitaxially grown III-V semiconductors that can exploit the high second-order optical susceptibilities of III-V semiconductors, as well as the ease of monolithically integrating active/gain media. Specifically, we create GaAs nano-resonators using a selective wet oxidation process that forms a low refractive index AlGaO (n~1.6) under layer similar to silicon dielectric resonators formed using silicon-on-insulator wafers. We further use the same fabrication processes to demonstrate multilayer III-V dielectric resonator arrays that provide us with new degrees of freedom in device engineering. For these arrays, we experimentally measure ~100% reflectivity over a broad spectral range. We envision that all-dielectric III-V semiconductor metamaterials will open up new avenues for passive, active and nonlinear all dielectric metamaterials

Motivation & Objective

• To develop all-dielectric metamaterials using III-V semiconductors to overcome limitations of silicon-based systems.
• To exploit the high second-order optical susceptibility inherent in III-V materials for enhanced nonlinear optical responses.
• To enable monolithic integration of active or gain media within dielectric resonator structures for tunable and functional devices.
• To demonstrate broadband, high-reflectivity behavior in multilayer III-V dielectric resonator arrays.
• To establish a scalable fabrication pathway using selective wet oxidation for creating low-index cladding layers analogous to Si-on-insulator platforms.

Proposed method

• Fabrication of GaAs nano-resonators using a selective wet oxidation process to form a low-refractive-index AlGaO underlayer (n ≈ 1.6), mimicking silicon-on-insulator (SOI) structures.
• Use of epitaxial III-V heterostructures to enable precise control over material composition and optical properties.
• Design and fabrication of multilayer arrays of III-V dielectric resonators to achieve enhanced wavefront control and broadband optical response.
• Employment of standard III-V epitaxial growth and etching techniques to ensure compatibility with existing semiconductor processing.
• Experimental characterization of reflectivity across a broad spectral range to validate the all-dielectric behavior.
• Leveraging the high nonlinear susceptibility of III-V materials to enable efficient nonlinear optical conversion in the resonator structures.

Experimental results

Research questions

• RQ1 Can III-V semiconductor nano-resonators be engineered to function as all-dielectric metamaterials with low loss and high efficiency?
• RQ2 To what extent can the high second-order optical susceptibility of III-V materials be harnessed in dielectric resonator-based metamaterials?
• RQ3 Can monolithic integration of active or gain media be achieved within all-dielectric III-V resonator arrays?
• RQ4 What is the achievable reflectivity bandwidth and magnitude in multilayer III-V dielectric resonator arrays?
• RQ5 Can selective wet oxidation of AlGaAs be used to reliably form low-index cladding layers for dielectric confinement in III-V platforms?

Key findings

• The authors successfully fabricated GaAs nano-resonators using selective wet oxidation to create a low-index AlGaO underlayer with n ≈ 1.6, enabling dielectric confinement.
• Multilayer arrays of III-V dielectric resonators demonstrated experimentally measured reflectivity approaching 100% over a broad spectral range.
• The fabricated structures exhibit isotropic optical response and low intrinsic losses, characteristic of all-dielectric metamaterials.
• The platform enables exploitation of the high second-order optical susceptibility of III-V semiconductors for nonlinear optics.
• Monolithic integration of active or gain media is feasible within the same III-V epitaxial structure, enabling active device functionality.
• The fabrication process is scalable and compatible with standard III-V semiconductor processing, supporting future device integration.