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Accurate measurement of the photonic crystal slab period using diffraction in the Littrow configuration
Published
Author(s)
John R. Lawall, Yiliang Bao, Jason Gorman
Abstract
Photonic crystal slab devices with subwavelength periods can be tailored to provide a remarkable range of functionalities, such as ultrahigh reflectivity in a structure only 200nm in thickness. Accurate measurement of the characteristics of these structures is essential to compare their performance to theoretical expectations, and to better understand the origin of unexpected behavior. Conventional measurements using scanning electron microscopy are limited at the level of tens of nanometers due to calibration issues and image distortion, and furthermore risk contaminating the sample by hydrocarbon deposition. In this work, we present a simple non-invasive method employing diffraction of a visible wavelength reference in Littrow configuration for measuring the period of a photonic crystal slab. We have measured periods of our devices with uncertainty below0.5nm, and expect that the uncertainty could be improved by an order of magnitude simply by use of a better rotation stage. In addition to facilitating device development, our approach can be used to explore possible variations in the period of the photonic crystal due to its operating environment and aging.
Lawall, J.
, Bao, Y.
and Gorman, J.
(2021),
Accurate measurement of the photonic crystal slab period using diffraction in the Littrow configuration, Optics Express, [online], https://doi.org/10.1364/OE.438308, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=932107
(Accessed October 8, 2025)