The evolution of a diffractive optical element (DOE) from a stand-alone component into an integral part of a micro-optical system can be a significant challenge. A Sandia National Laboratories research program is presented to illustrate ways that system considerations modify integrated DOE material choices, layout configurations, and ultimately DOE component performance.
This project employs an array of resonant subwavelength gratings (RSGs), also known in the literature as guided mode resonance filters, corrugated dielectric waveguides, and corrugated waveguides. This optical component acts as an extremely narrow wavelength and angular band reflector, or mode selector. Theoretical studies predict that the infinite, laterally extended component can reflect 100% of the resonant light while transmitting the balance of the other wavelengths. Previous researchers' experimental confirmation of this remarkable prediction has been impacted primarily by packaging and fabrication challenges.
The program at Sandia is a normal incidence
array configuration RSG where each array element resonates with
a distinct wavelength to act as a dense array of wavelength and
polarization selective reflectors. Design goals are peak reflectance
near unity, narrow spectral bandwidth, and low sideband reflectivity
for use in an arrayed grating structure. Theoretical responses
for infinite-extent and finite-extent components will be presented
along with measured results.
©Copyright 1999 KSU Department of Physics