The Optical Metamaterials Program was formed at Oak Ridge National Laboratory (ORNL) in 2009 to advance the application of metamaterials to the Nation's energy-related challenges. Leveraging the world's most powerful supercomputer for scientific study, a world-class nanofabrication facility (CNMS), and a strong industry-led consortium, the Optical Metamaterials Program (OMP) at ORNL is developing metamaterials to overcome core technology challenges being addressed by the Department of Energy.
What are Metamaterials?
Metamaterials are man-made composite materials constructed with nanometer-sized periodic structures containing both dielectric and metal materials. These structures can produce materials with negative index of refraction - a unique material property that does not occur naturally. Metamaterials exhibit bizarre optical properties that challenge our fundamental understand of the interaction between light and matter. In a metamaterial, light refracts in the opposite direction, waves are converged by a planar interface, normally attractive quantum forces (Casimir forces) become repulsive, doppler shifting is reversed, and a variety of other remarkable phenomena are observed.
Common structure of a metamaterial for 1.5micron wavelength light. (a) theoretical parameters (b) physical devices - courtesy of G. Dolling, C. Enkrich, M. Wegener, C. M. Soukoulis and S. Linden, “A low-loss negative index metamaterial at telecommunication wavelengths,” Opt. Lett. 31, 1800 (2006).
The possibility of negative index materials (NIM) was first predicting in 1967 by Victor Veselago but was only recently demonstrated for microwave and near-IR radiation. A worldwide effort is underway to develop bulk materials that can demonstrate these phenomena with visible light, low optical loss, and broad spectral response.
The goal of the Optical Metamaterials Program is to realize the creation of metamaterial coatings and bulk materials that have specific applications to the Nation's energy-related challenges. These applications include:
- Metamaterial coating for improved solar cell efficiency
- Nanocrystalline capture in metamaterials for enhanced thermophotovoltaic cells
- Metamaterial microlenses and lens coatings for improved efficiency Light Emitting Diodes (LEDs)
- Metamaterial sensors for the emerging SmartGrid
- Metamaterials for high efficiency computing and data storage
- Wireless energy transfer coupling based on metamaterial concentrators and collectors
- Subwavelength optical microscopy
- Optical traps and delays for quantum computing
- Enhanced reverse Casimir effect for nano-mechanical devises
- Basic science advances
ORNL has a well established history as a leader in material research and innovation. Building on this expertise, the ORNL research team consists of a half-dozen Ph.D. scientists working with academia and industry to advance the state-of-the-art in metamaterial modeling, fabrication, and application. Nanofabrication techniques unique to ORNL - such as an advanced method for producing large-area, highly periodic, nonstructured surfaces (see figure below) - are being utilized and developed by a diverse group of technologists with extensive experience with the Dept. of Energy's core technical challenges.
Unique glass drawing facilities allow large-area nanostructured surfaces to be prepared with exceptional periodicity. These structures can form the base of a metamaterial design or, alternately, be utilized as a tool in subsequent nanofabrication (i.e. stylus for nano-imprint lithography).
The Optical Metamaterials Program works closely with a number of industry partners, universities, and government facilities. Some of these key partners include:
- Duke University - Duke's Center for Metamaterials and Integrated Plasmonics is a powerhouse in the rapidly advancing field of metamaterials. Under the leadership of metamaterials pioneer, Dr. David Smith, the center possesses theoretical and fabrication expertise that is synergistic with ORNL's computational and nanofab facilities. Together, Duke and ORNL are teaming to develop metamaterial designs targeted at higher efficiency LED lighting, improved solar cell performance, and other DOE applications.
- L-3 PHOTONICS - With over 65,000 employees, L-3 is one of the largest government contractors in the U.S. It's major photonics division, L-3 PHOTONICS is responsible for the development of a variety of optical communication and sensing technology. Together, L-3 PHOTONICS and ORNL are teaming to develop metamaterials for innovative optical fiber and planar waveguide sensors. These sensors have near-term applications to chemical detection, nuclear material monitoring and safeguards, and electrical grid monitoring critical to the DOE mission.
- The Center for Nanophase Materials Sciences (CNMS) - The CNMS at ORNL is a world-class facility dedicated to fabrication and measurement at the nanoscale level. Operating as a national user facility, the CNMS supports a multidisciplinary environment for research to understand nanoscale materials and phenomena. The unique capabilities of CNMS supplement ORNL's internal nanofab capabilities. This combination allows ORNL, and it's partners, to explore numerous metamaterial fabrication approaches.
- The National Center for Computational Sciences (NCCS) - ORNL's NCCS is the fastest, most powerful, supercomputer for non-classified scientific research in the world. A government sponsored user-facility, this resource is leveraged by the Optical Metamaterials Program to run the computationally intentensive models required to predict photonic performance for a given metamaterial design.