METAMATERIALS FOR NONLINEAR COUPLING AND DECOUPLING OF OPTO ELECTRONIC AND MECHANICAL SYSTEMS
Abstract
The project focuses on developing a fundamental understanding of novel nonlinear metamaterials. Metamaterials are artificial materials that enable dynamic manipulation of energy and energy transfer that is outside the capabilities of any single material, no matter how exotic. Metamaterials are often multifunctional because they operate in the spaces between normal (linear)materials. In the present study, we are interested in nonlinear coupling of electromagnetic radiation(light) to materials. We will pinch light to create new phenomena that will eventually lead to the nextgeneration of opto-electronic and opto-mechanical systems. The foundation of this project is the PI’sdevelopment of a unique process for forming polyhedron Au mesoscopic structures on Si, which werefer to as Au pyramids. The pyramids have a unique channel-like morphology that enhances the surfaceplasmon polarition (SPP) activity and the number of SPP modes they can support. The SPP are excitedwith light, such that by combining Au and Si, we achieve nonlinear coupling of the charge carriers of thetwo materials. Furthermore, Au and Si combine to form a metamaterial that nonlinearly interacts withthe terahertz (THz) region of the electromagnetic spectrum. This combination of materials also interactswith infrared (IR) radiation and is the foundation of metamaterials used for metamirrors –metamaterials with nonlinear reflective properties or in some cases, the ability to suppress unwantednonlinear optical behavior.While the goal of this research is fundamental scientific discovery, we have an eye on how ourdiscoveries can lead to new technologies or, conversely, use technological goals to help focus basicresearch. To this end, we are interested in opto-electronic THz communication devices, such as fastcoupledTHz-optical modulators, multi-functional modulators that add dynamic beam steering, andhigh-speed electronics to THz couplers. As for opto-mechanical systems, we see opportunities toproduce surfaces with the ability to effectively reflect 100 percent IR radiation and simultaneously control thedistribution of light pressure, i.e. momentum transfer, both of which are critical to the development ofthe Starshot lightsail. While the two applications appear to be on opposite sides of the scientificspectrum, outcomes of the THz studies, for good or bad, will benefit the lightsail studies or vice versa. Ineffect, we envision multifunctional scientific discovery, much like metamaterials.The Au pyramids on Si will serve as the metamaterials substrate, so to speak, because it alonecannot produce the degree of nonlinearity we are striving to achieve. We will enhance their nonlinearproperties by applying additional coatings of dielectrics, semiconductors, and metals to them. Toproduce opto-electronic metamaterials with nonlinear signatures in the THz spectrum, multilayercombinations of plasmonic metals (Au, Ag, Al, Mg) and semiconductors (GaN, ZnO, SnO, TiO2, Al2O3,etc.) will be used with the pyramids, achieving nonlinearity by virtue of tailored carrier dynamics. Asimilar approach can produce opto-mechanical metamaterials, but in this case, the role of the multilayermetal coatings is to suppress the nonlinear coupling to surface plasmon polaritons of Au, which have theunwanted effect of converting electromagnetic radiation into Joule heating. Conversely, we will usemultilayer dielectric coatings, or in combination with metal layers, to control and disperse light pressureacross the sample surface, thereby controlling the magnitude and direction of the reflected light(momentum distribution across the lightsail). Because the coupling of SPP to light is also dependent onthe shape of the structures, we will use lithography to control the location of the pyramids on the Sisurface, thereby producing patterns that enhance SPP coupling in the THz and IR spectral regions.
Document Details
- Document Type
- DoD Grant Award
- Publication Date
- Mar 07, 2023
- Source ID
- FA95502110456
Entities
People
- David N McIlroy
Organizations
- Air Force Office of Scientific Research
- Oklahoma State University–Stillwater
- United States Air Force