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Optimising the AR Engraved Structure on Light-Guide Facets for a Wide Range of Wavelengths

1
Photonics and Electro-Optics Engineering Unit, Ben-Gurion University, Beer-Sheva 8410501, Israel
2
Department of Electrotechnics and Electronics, Academic College Sami Shamoon, Beer-Sheva 8410802, Israel
*
Author to whom correspondence should be addressed.
Optics 2021, 2(1), 25-42; https://doi.org/10.3390/opt2010002
Received: 9 December 2020 / Revised: 22 December 2020 / Accepted: 25 December 2020 / Published: 31 December 2020
The present study is aimed at designing anti-reflective (AR) engraving on the input–output surfaces of a rectangular light-guide. We estimate AR efficiency, by the transmittance level in the angular range, determined by the light-guide. Using nano-engraving, we achieve a uniform high transmission over a wide range of wavelengths. In the past, we used smoothed conical pins or indentations on the faces of light-guide crystal as the engraved structure. Here, we widen the class of pins under consideration, following the physical model developed in the previous paper. We analyze the smoothed pyramidal pins with different base shapes. The possible effect of randomization of the pins parameters is also examined. The results obtained demonstrate optimized engraved structure with parameters depending on the required spectral range and facet format. The predicted level of transmittance is close to 99%, and its flatness (estimated by the standard deviation) in the required wavelengths range is 0.2%. The theoretical analysis and numerical calculations indicate that the obtained results demonstrate the best transmission (reflection) we can expect for a facet with the given shape and size for the required spectral band. The approach is equally useful for any other form and of the facet. We also discuss a simple way of comparing experimental and theoretical results for a light-guide with the designed input and output features. In this study, as well as in our previous work, we restrict ourselves to rectangular facets. We also consider the limitations on maximal transmission produced by the size and shape of the light-guide facets. The theoretical analysis is performed for an infinite structure and serves as an upper bound on the transmittance for smaller-size apertures. View Full-Text
Keywords: anti-reflective; light transmission; optical waveguide anti-reflective; light transmission; optical waveguide
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MDPI and ACS Style

Gurwich, I.; Greenberg, Y.; Harush, K.; Tzabari, Y. Optimising the AR Engraved Structure on Light-Guide Facets for a Wide Range of Wavelengths. Optics 2021, 2, 25-42. https://doi.org/10.3390/opt2010002

AMA Style

Gurwich I, Greenberg Y, Harush K, Tzabari Y. Optimising the AR Engraved Structure on Light-Guide Facets for a Wide Range of Wavelengths. Optics. 2021; 2(1):25-42. https://doi.org/10.3390/opt2010002

Chicago/Turabian Style

Gurwich, Ioseph; Greenberg, Yakov; Harush, Kobi; Tzabari, Yarden. 2021. "Optimising the AR Engraved Structure on Light-Guide Facets for a Wide Range of Wavelengths" Optics 2, no. 1: 25-42. https://doi.org/10.3390/opt2010002

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