EAGER: Properties of ultra-sparse resonant photonic lattices

University Of Texas At Arlington, Arlington TX

Investigators

Abstract

EAGER: Development of ultra-sparse nanoscale resonant reflectors and polarizers The objective of this proposal is to design, fabricate, and characterize wideband resonant reflectors and polarizers that require extremely small amounts of matter in their embodiments. Polarizers are essential components in every-day optical systems. They are used, for example, in liquid-crystal television screens and computer and cell-phone displays. Similarly, reflectors are widely used in optical imaging systems, telecommunications, and laser technology. Shown here is the remarkable and counterintuitive fact that a nanoscale periodic layer that is 95% empty space can reflect light at 100% efficiency across a 100-nm-wide spectral band. This simple device exhibits impressive polarizing performance as well. We call these elements ultra-sparse reflectors and polarizers. As these devices incorporate no metals, they are lossless and thus operate on incident light with high efficiency and without generating any heat. The project contributes to fundamental understanding of this class of devices and thereby lays foundation for its applications in common photonic systems. The proposed research project will focus on a spectral region spanning from the visible region into the infrared range where common telecommunication systems operate. However, it is noted that the fundamental physics of these elements does not limit their deployment to these regions. Hence, future developments in longer wavelength regions such as the far-infrared and terahertz bands may enable compact low-loss elements to be realized in these regions as well. The proposed project therefore lays a foundation for devices with new operational regimes and attendant possible applications in multiple practical spectral regions. We introduce ultra-sparse reflectors and polarizers based on original new ideas in photonic device engineering. Under the project, prototype devices will be fashioned in nearly lossless semiconductors and dielectrics as membranes surrounded by air or glass host media. Initial focus is on spectral operation within the 400-2400 nm region. Using available nanofabrication processing facilities, we will fabricate representative devices as proof-of-concept prototypes, measure their spectral response, and compare with theoretical predictions. From a fundamental physics standpoint, it is extremely significant that the wideband spectral expressions presented can be generated in these minimal resonance systems. The proposed research is justified on that basis alone. Therefore, the project has strong potential to advance the state of knowledge and understanding in nanophotonic resonance systems. Contrary to widely accepted views, interference between two grating-ridge located Fabry-Perot modes is not the cause of the observed wideband reflection. Therefore, it follows logically that the number of such modes in a grating ridge is immaterial as far as the fundamental physics is concerned. We show that wideband reflectors are indeed achievable with a single supported ridge mode. This fact allows us to conceptualize resonant elements that are mostly free space with minimal physical bulk, an extremely interesting and important finding. To improve the state of understanding in this field, we plan on wide dissemination of the results of the research. This will broaden the design space available to scientists and engineers innovating within this device class.