Nonlinear Metamaterials for Holography (1512.07899v1)

Abstract: A hologram is an optical element storing phase and possibly amplitude information enabling the reconstruction of a three dimensional image of an object by illumination and scattering of a coherent beam of light, and the image is generated at the same wavelength as the input laser beam. In recent years it was shown that information can be stored in nanometric antennas giving rise to ultrathin components. Here we demonstrate nonlinear multi-layer metamaterial holograms where by the nonlinear process of Third Harmonic Generation, a background free image is formed at a new frequency which is the third harmonic of the illuminating beam. Using e-beam lithography of multilayer plasmonic nanoantennas, we fabricate polarization-sensitive nonlinear elements such as blazed gratings, lenses and other computer-generated holograms. These holograms are analyzed and prospects for future device applications are discussed.

• The paper reveals an innovative use of nonlinear metasurfaces to achieve third harmonic generation for efficient hologram production.
• It employs polarization-sensitive, V-shaped gold nanoantennas fabricated via multilayer e-beam lithography to produce phase shifts up to 2π.
• The study lays a foundation for advanced applications in volumetric data storage and dynamic holographic imaging with minimal background interference.

Nonlinear Metamaterials for Holography: An Expert Analysis

The paper "Nonlinear Metamaterials for Holography" by Euclides Almeida, Ora Bitton, and Yehiam Prior presents a comprehensive exploration of the use of nonlinear metamaterials in holography by harnessing third harmonic generation (THG). The researchers demonstrate the design and fabrication of novel multilayered plasmonic metamaterials that enable the generation of holographic images at frequencies different from the input beam, a significant divergence from traditional holography.

Key Contributions

The primary innovation discussed is the use of nonlinear metasurfaces to manipulate the phase of light in a manner that results in efficient third harmonic generation. Through meticulous design of polarization-sensitive, multilayer plasmonic nanoantennas fabricated using e-beam lithography, the paper showcases the ability to create computer-generated holograms capable of producing high-resolution images without background noise. This is accomplished by encoding phase information within sub-micron scale nanoantennas, which is potent enough to generate nonlinear imaging at three times the fundamental frequency of the illumination source.

Methodology and Results

The design strategy leverages linearly polarizable V-shaped gold antennas, whose structural parameters—arm length and angular orientation—are tuned to manipulate plasmonic resonances across the near-infrared spectrum. These antennas enable significant phase shifts (up to 2π) in the nonlinear regimes, crucial for efficient hologram generation. Experimentally, these antennas demonstrate strong third-order nonlinear susceptibility, facilitating robust THG.

Sample preparation involves meticulous multilayer e-beam lithography to construct composites of nanoantennas on silica substrates. The process ensures precise control over inter-layer alignment and spacing, vital for maintaining optical coherence across layers and enhancing the resolution and depth perception of holograms.

Holograms are designed to respond to specific polarizations, incorporating multilayer encoding to project different images based on input beam polarization, thus enabling 3D and dynamic imaging potentials. The experimental demonstrations include holographic projections of multifaceted images, such as Hebrew letters and iconic drawings, controlled by varying polarization states. Computational modeling via FDTD simulations corroborates the empirical observations and provides a detailed understanding of phase and amplitude control across the fundamental and THG frequencies.

Implications and Future Directions

This research opens pathways for practical application in volumetric data storage and the development of sophisticated optical devices like lenses and blazed gratings operating on nonlinear principles. The ability to generate holograms at distinct frequencies further paves the way for reducing background interference, a notable limitation of conventional linear holography.

From a theoretical perspective, the paper underscores the vast potential of nonlinear photonic crystals and metasurfaces for enhancing light-matter interaction at nanoscales. It sets the foundation for further exploration into complex nonlinear processes and their integration with quantum and classical photonic systems.

Looking ahead, future research can explore expanding the spectral range of these nonlinear holograms, exploring alternative materials for enhanced nonlinear efficiencies, and integrating these mechanisms into broader photonic circuitry and systems. As such, the implications extend into the field of ultrafast photonics and dynamic display technologies, marking a promising trajectory for metamaterials research within applied and fundamental physics.