Princeton University Office of Technology Licensing and Intellectual Property
Fourth Floor, New South Building
Princeton, New Jersey 08544-0036
Laurie Tzodikov
Phone: (609) 258-7256
Email: tzodikov@princeton.edu
Princeton University Invention # 09-2504
Scientists in the Princeton Center for Theoretical Science, the Department of Chemistry, and the Department of Physics, Princeton University, have discovered an efficient method for designing dielectric materials with optimal photonic band gap (PBG) properties based on any chosen point pattern, no matter the rotational symmetry or translational order. A PBG material is a heterostructures consisting of two or more dielectric materials (one of which can be vacuum or air) in an interpenetrating arrangement that causes the index of refraction to vary on a length scale comparable to the wavelength of the radiation to be controlled. For certain arrangements, a dielectric heterostructure creates a full photonic band gap, a range of frequencies for which electromagnetic wave propagation is prohibited for all directions and polarizations. The presence of a full photonic band gap in the dispersion relation of the electromagnetic field can be exploited in new technological applications, including efficient radiation sources, sensors, optical computer chips and telecommunications devices such as optical fibers and waveguides, T-branches, channel-drops, etc.
The existence and properties of a band gap depend on the symmetry of the arrangement of the dielectric materials. Because there are so many degrees of freedom in choosing an arrangement, including its rotational symmetry, its long-range translational order, and the precise locations of its components, a method is needed for identifying the arrangement with the widest possible band gap from the uncountable number of choices available. A common way of searching for an optimal structure is to choose a point pattern with the desired rotational symmetry and translational order and seek a ``decoration” – a specific configuration of dielectric materials – to be placed around each point that produces the widest possible full photonic band gap. Generally, the search for optimal design has been guided by exhaustive trial and-error approaches although, recently, highly computer-intensive search algorithms have been for maximizing the band gaps, including the projected generalized gradient ascent algorithm; level set methods, stochastic optimization techniques and Voronoi tessellations. All the optimization work to date, though, has been restricted to simple periodic (crystalline) patterns and, in most cases, in two dimensions.
The resulting dielectric heterostructures, known as photonic crystals, are restricted mathematically to having only certain symmetries, insuring that the band gap properties are different for light propagating along different directions with respect to the crystal axes of the heterostructure. Although this anisotropy suffices for some applications, it is disadvantageous for others, such as highly-efficient
isotropic radiation sources and waveguides with arbitrary bending angle.
This invention is a computationally simple, general optimization method for designing network arrangements of dielectric materials based on any type of point pattern in one, two, or three dimensions with optimal band gaps that block both polarizations of light. Numerical experiments were performed to show that the method reproduces the optimal structures for periodic patterns that had been identified using computer-intensive approaches. Then, the method was applied to non-periodic point patterns to design many new optimal structures that were not known previously, including the first quasiperiodic and isotropic disordered hyperuniform heterostructures with wide photonic band gaps that block all polarizations. Because the method requires less computational resources, it can be used to design both better and larger PBG heterostructures than can be obtained using other existing optimization techniques.
Princeton is currently seeking commercial partners for the further development and commercialization of this opportunity. Patent protection is pending.
For more information on Princeton University invention # 09-2504 please contact:
Laurie Tzodikov
Office of Technology Licensing and Intellectual Property
Princeton University
4 New South Building
Princeton, NJ 08544-0036
(609) 258-7256
(609) 258-1159 fax
tzodikov@princeton.edu