The ability to design and fabricate materials with new functionalities opens the door to a new world of possibilities. They can be tailored to either augment the functionality of existing devices or create new devices with superior performances. EnMats are broadly defined to include, but are not limited to, metamaterials (both metallic and dielectric), scattering surfaces and volumes, holographic structures, and diffractive elements.
The Defense Advanced Research Projects Agency (DARPA) announced a new program designed to better understand and ultimately improve metamaterials. The program could lead to improvements in a number of areas, including imaging, thermal control and frequency conversion. NLM program, seeks to finally develop theory-anchored models that can expand the state of the art in already-observed phenomena while pointing to never-before-realized and new functionality.
The goal of NLM is to integrate emerging phenomena with fundamental models that can describe and predict new functionality. These models will provide design tools and delineate the performance limits of new engineered light-matter interactions. Important applications to be addressed in the program include synthesizing new material structures for sources, non-reciprocal behavior, parametric phenomena, limiters, electromagnetic drives, and energy harvesting.
If we could have a space drive that did not use fuel then we could accelerate for decades using a nuclear power source. This would allow a spacecraft with a tiny amount of propulsion to accelerate to near light speed. DARPA has been funding the Nascent Light-Matter Interactions (NLM) project for about three years. This project is looking for functional variations of the super controversial EMDrive. EMDrive was first created twenty years ago and claimed that a conical copper device bounced magnetic radiation in the chamber to generate propulsion without using fuel. There are reports that the DARPA project was working with researchers in Spain who claim that forces of 0.1 newtons were generated. This needs to be confirmed. If confirmed then the system would be 5 times more powerful than the 0.02 newtons of some commercial ion drives.
The new program should benefit existing programs, such as EXTREME, which focuses on specific uses for engineered materials. The goal of the EXTREME Program is to develop new optical components, devices, systems, architectures and design tools using Engineered Optical Materials (EnMats) to enable new functionality and/or vastly improve size, weight, and power characteristics of traditional optical systems.
DARPA says that the EXTREME project could introduce a new era in optics and imagers for national defense. EXTREME optical components would be lighter and smaller, enabling miniaturization of imaging systems for intelligence, surveillance, and reconnaissance (ISR) applications. The multifunctional nature of these devices could offer improvements in a wide variety of imaging systems by reducing size and weight without compromising performance for systems as diverse as night vision goggles, hyperspectral imagers, and IR search and track systems.
The DARPA NLM project is currently funded until May 2021. Mike McCulloch is the current DARPA EmDrive project leader. Mike presented some interim results in an embedded video below.
Nascent Light-Matter Interactions (NLM) program
Recent advances in our understanding of light-matter interactions, often with patterned and resonant structures, reveal nascent concepts for new interactions that may impact many applications. Examples of these novel phenomena include interactions involving active media, symmetry, non-reciprocity, and linear/nonlinear resonant coupling effects.
Insights regarding the origins of these interactions have the potential to transform our understanding of how to control electromagnetic waves and design for new light-matter interactions. The goal of NLM is to bring together and integrate these emerging phenomena with fundamental models that can describe and predict new functionality. These models will provide design tools and delineate the performance limits of new engineered light-matter interactions. Important applications to be addressed in the program include synthesizing new material structures for sources, non-reciprocal behavior, parametric phenomena, limiters, electromagnetic drives, and energy harvesting.
In the last few years, our understanding of how materials interact with electromagnetic waves has resulted in nascent concepts that could develop into fundamentally new predictive models for light-matter interactions. Examples include: Resonant cavity-enhanced phenomena; Breaking Lorentz reciprocity and the role of gain and symmetry; The role of epsilon-near-zero materials; Developments in non-reciprocal structures; New approaches to managing photon density of states; New models for both nonlinear and non-scattering structures; Freeform optimized structures for wavefront control; and Opto-nano-mechanical phenomena for new properties and structure assembly.
A unique class of engineered light-manipulating materials, known as metamaterials or structured materials, makes use of patterns of strongly interacting wavelength or sub-wavelength-sized elements. Because of these intricate internal and surface structures, new properties have emerged, some exhibiting behavior that has resulted in rewriting long-understood “laws” for how light and other electromagnetic (EM) waves interact with materials. These materials have been opening up new options for controlling EM waves in many technological arenas, among them imaging, thermal control, and frequency conversion. Specific applications include night-vision, heat reflection and management in aircraft engines, and temperature regulation of electronics on satellites in the hot-and-cold extremes of space.
Although researchers have been taking steps toward putting these materials to practical use, they remain puzzled about the optimal structure designs for desired matter-light interactions. They have yet to model the materials in ways that enable predictions about how specific structured materials will behave under different conditions, such as increased illumination intensities.
Each of these examples provides new possibilities to control electromagnetic waves while also suggesting opportunities for new wave-matter interactions. To develop new and systematic approaches to the design of structures and materials, a predictive model providing a design tool is required.
To fill in these knowledge gaps, DARPA has announced the Nascent Light-Matter Interactions (NLM) program, which seeks to finally develop theory-anchored models that can expand the state of the art in already-observed phenomena while pointing to never-before-realized and new functionality.
“Recent advances in our understanding of light-matter interactions have revealed nascent concepts that could yield new materials with properties way beyond anything we have now,” said Mike Fiddy, DARPA program manager. “Through NLM we aim to identify building blocks to better understand the physics of 2-D and 3-D structured materials, which can then lead to a systematic design approach for controlling electromagnetic waves through these materials. The end goal is to equip designers with rigorous predictive models and design tools to answer the currently elusive question: ‘If I want a material with X property, how do I build it?’”
For example, can we open new pathways for designing materials that provide more efficiency in up-conversion or down conversion of frequencies, which could benefit military capabilities such as night vision? “At the moment, the state-of-the-art of these complicated structures is you pump them with one frequency and they’ll emit maybe 10 percent at another frequency, but they require lots of power in the process,” he said. “Can we develop design tools to create materials with 80, 90, or 100 percent efficiency in converting infrared light into visible light that require very little or no power?”
As Fiddy sees it, lessons learned in the NLM program also might help engineers design better materials, for example, that automatically block the frequency of a laser if it’s shined directly into the eye. Another example is managing extremely hot temperatures, such as those found in turbine aircraft engines. New engineered materials could help precisely manage temperatures in critical hot parts of the engine, which in turn could lead to more efficiency, thus reducing fuel and maintenance costs.
“Similarly, on satellites, as they orient toward the sun they can get ‘cooked’ and when they are out of the sun they are very cold,” Fiddy said. “Those big temperature extremes have to be controlled somehow in the satellite’s design. But if there were more efficient ways of radiating away the sun’s heat using structured materials, that would be very valuable. A general approach to solving this problem could be beneficial for keeping computer chips cool while at the same time opening up new ways to harvest electromagnetic energy.”
It could take years to realize such possibilities, Fiddy noted, but he hopes the NLM program will deliver new levels of understanding and modeling tools that could hasten that day.
For example, consider metamaterials that have extended our ability to control electromagnetic waves in new ways. Unlike traditional composite structures, metamaterial designs have emerged from, and rely heavily on circuit theory models and “abstracted” circuit elements. These serve as functionally focused artificial atoms, thereby extending what is possible with “naturally” occurring atoms and molecules. These structured meta-atoms frequently exploit designed resonant scattering phenomena and are useful material building blocks.
The NLM program will unfold in three phases. The first will challenge performers to develop a model and show that it can predict new phenomena and serve as a design tool. The second phase will push researchers to test the models’ actual utility for identifying new materials useful for specific applications. The goal for Phase 3 is to identify specific challenge problems and tie selected performers and their respective focus and applications to the operational needs of DoD stakeholders
Columbia Engineers Win $4.7M DARPA Grant to Revolutionize Augmented Reality Glasses in 2018
Imagine driving along the highway with directions and other pertinent information (think gas stations) appearing “on” your glasses so you don’t have to look away from the road. Or building a complicated DIY project with step-by-step instructions appearing “on” your glasses. Or being a first-responder unsure which way to go, receiving information from central headquarters “on” your glasses. Augmented reality (AR) glasses can already do all of this, but current models are very heavy, big and clunky, and use a lot of power. Most people, especially those in the field, cannot wear them comfortably for very long.
An interdisciplinary Columbia Engineering team is working with colleagues at Stanford, UMass Amherst, and Trex Enterprises Corporation to come up with an alternative solution. Thanks to a $4.7 million, four-year grant from DARPA, they are developing a revolutionary lightweight glass that is able to dynamically monitor the wearer’s vision and display contextual images that are vision-corrected.
Proposed augmented reality (AR) glass based on Silicon Nitride integrated photonics. The AR glass consists of a 2D array of pixels, RGB and NIR lasers, a NIR detector, a NIR isolator, electronic circuits, and control software.
“We are creating a game-changer, a completely novel glass design that enables high resolution projection and detection of light with no moving parts,” says Michal Lipson, Eugene Higgins Professor of Electrical Engineering at Columbia, a pioneer in nanophotonics who is leading the team. “Our design will be a key technology enabler for the Department of Defense, industry, and the general public. Our ultimate deliverable will be an ultrahigh-resolution, see-through, head-mounted display with a large field of view and vastly reduced SWaP (size, weight, and power consumption), coupled with the ability to correct users’ ocular aberrations in real time and project aberration-corrected visible contextual information onto the retina.
The technology leverages recent work by the Columbia Engineering team, including James Hone (mechanical engineering), Nanfang Yu (applied physics), and Dimitri Basov (physics, Arts & Sciences), who have developed novel engineered optical materials (EnMats) that include new phase-transition correlated oxides and 2D excitonic transition metal dichalcogenides (TMDs). These EnMats provide extremely high electro-optic response and have very low losses in the visible (VIS) and near-infrared (NIR). Silicon nitride (SiN) integrated photonics will serve as the backbone onto which these EnMats will be incorporated to realize the AR glass.
The project also draws on other Columbia Engineering strengths, including work by Lipson and Alex Gaeta (applied physics), who have demonstrated high technological capabilities of SiN photonics for the visible (VIS) and near-infrared (NIR) spectral ranges, by Nanfang Yu, who works on flat optics, or “metasurfaces,” that are able to mold optical wavefronts into arbitrary shapes, and by Harish Krishnaswamy (electrical engineering) and Lipson, who lead the field in device and circuit design and large-scale nanofabrication to demonstrate phased arrays in the VIS and NIR.
The proposed AR glass relies on the ultrafast generation of arbitrary wavefronts, both in VIS and NIR. Fast arbitrary wavefront generation in these spectral ranges has been one of the major challenges in optics due mainly to a lack of actively tunable optical materials. Commercially available spatial light modulators based on liquid crystal cells and MEMS mirror arrays do not solve the problem because they are limited in modulation speed and spatial resolution.
“We are proposing an ultra-compact platform for arbitrary wavefront generation with high speed that is based on tunable metasurfaces in the VIS and NIR,” says Yu, assistant professor of applied physics. “The metasurfaces are based on two critical innovations we’ve made at Columbia Engineering: our EnMats with highly tunable complex optical refractive indices and optical resonators that further enhance the electro-optic effect of the EnMats.”
The AR glass’s 2D array of pixels are based on VIS and NIR electrically tunable SiN resonators coated with thin-film EnMats. Each pixel includes RGB (red-green-blue light for projecting the image) and NIR (for characterizing ocular aberrations) optical phased arrays. The AR glass also contains one optical isolator to distinguish between NIR light projected into the eye and NIR light reflected from the retina. The isolator enables simultaneous light projection and detection in the NIR. “We will couple laser light into a bus waveguide, distribute it over a network of branch waveguides covering the entire surface of the AR glass, evanescently couple it into the SiN resonators, and then scatter it into the eye,” Lipson notes.
The team plans to develop a scalable fabrication process that is based on standard CMOS techniques, such as Deep UV lithography, and well-established procedures, such as dry transfer methods, to integrate the EnMats into the SiN integrated photonics platform. They will also design analytical and computational tools for modeling large resonator arrays and dynamics of device performance. “The multifunctionality of our nanostructured AR glass is enabled by extreme capabilities that cannot be achieved using traditional optical elements,” says Lipson. “Our system incorporates the capabilities of wavefront sensing and correction for lower and higher order ocular aberrations in real time, capabilities that no other display technology provides and that have been shown to be critical for clear or even ‘supernormal’ vision of images.”
MOD-EnMat technology in Nautilus
The transformative technology behind Nautilus are the ultralight, very large-aperture engineered material multi-order diffractive lenses (MOD-EnMat) developed at The University of Arizona’s College of Optical Sciences. Traditional lenses use refraction – the change of light’s direction as it enters a medium with different refractive index – to focus light onto the focal plane, thereby creating images. However, large lenses are exceedingly difficult to manufacture.
The MOD-EnMat lenses (multi-order diffractive engineered material lenses) are very light-weight diffractive-transmissive alternatives to the heavy reflective elements (mirrors) used in state-of-the-art ground- and space-based telescopes. Technology similar to MOD-EnMat lenses is used in some commercial optics, including high-quality Canon EF photo-lenses. The optimized multi-order design of these lenses provides essentially achromatic, diffraction-limited performance.
Plymouth Researchers Awarded $1.3M Grant for Light-Based Space Travel in 2018
Researchers at the University of Plymouth (UP) have been awarded a $1.3 million grant from the U.S. Defense Advanced Research Projects Agency (DARPA) to advance nonfuel propulsion for space travel. UP’s Mike McCullough believes that light can be converted into thrust through the use of quantized inertia (QI). The QI theory predicts that objects can be pushed by differences in the intensity of so-called Unruh radiation in space, similar to the way in which a ship can be pushed toward a dock because there are more waves hitting it from the seaward side.
The theory has already predicted galaxy rotation without dark matter, and if a system is accelerated enough — such as a spinning disc or light bouncing between mirrors — the Unruh waves it sees can be influenced by a shield. Therefore, if a damper is placed above the object, it should produce a new kind of upward thrust. “I believe QI could be a real game-changer for space science,” McCullough said. “I have always thought it could be used to convert light into thrust, but it also suggests ways to enhance that thrust. It is hugely exciting to now have the opportunity to test it.”
The research is being funded through DARPA’s Nascent Light-Matter Interactions (NLM) program, which aims to improve the fundamental understanding of how to control the interaction of light and engineered materials. McCulloch will collaborate with experimental scientists from the Technische Universität Dresden in Germany and the University of Alcala in Spain.
Over the first 18 months, the Plymouth team will seek to develop a fully predictive theoretical model of how matter interacts with light using the quantized inertia model, providing a new predictive tool for light-matter interactions. A series of experiments will then be conducted in Germany and Spain to test whether the thrust is specifically due to quantized inertia and whether it can be enhanced significantly. “Ultimately, what this could mean is you would need no propellant to launch a satellite,” McCulloch said. “But it would also mean you only need a source of electrical power — for example, solar power — to move any craft once it is in space. It has the potential to make interplanetary travel much easier and interstellar travel possible.”