Title

Optimal-Design For Antireflective Tapered 2-Dimensional Subwavelength Grating Structures

Authors

Authors

E. B. Grann; M. G. Moharam;D. A. Pommet

Comments

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Abbreviated Journal Title

J. Opt. Soc. Am. A-Opt. Image Sci. Vis.

Keywords

DIFFRACTIVE OPTICS; SUBWAVELENGTH GRATINGS; EFFECTIVE-MEDIUM THEORY; GRADIENT INDEX; ANTIREFLECTION; RELIEF GRATINGS; SURFACES; Optics

Abstract

Techniques for the design of continuously tapered two-dimensional (2D) subwavelength surface-relief grating structures for broadband antireflection surfaces are investigated. It has been determined that the Klopfenstein taper [Proc. IRE 44, 31 (1956)] produces the optimum graded-index profile with the smallest depth for any specified minimum reflectance. A technique is developed to design the equivalent tapered subwavelength surface-relief grating structure by use of 2D effective-medium theory. An optimal Klopfenstein tapered 2D subwavelength grating is designed to reduce the Fresnel reflections by 20 dB over a broad band from an air-substrate (n(s) = 3.0) interface. The performance is verified by use of both a 2D effective-medium-theory simulation algorithm and rigorous coupled-wave analysis. These structures are also shown to achieve this low reflectance over a wide field of view (theta(FOV) > 110 degrees). The pyramidal spatial profile, which has generally been assumed to produce the optimal broadband antireflection grating structure, is shown to require a significantly larger depth to achieve the same performance as a Klopfenstein-designed tapered antireflection grating structure.

Journal Title

Journal of the Optical Society of America a-Optics Image Science and Vision

Volume

12

Issue/Number

2

Publication Date

1-1-1995

Document Type

Article

Language

English

First Page

333

Last Page

339

WOS Identifier

WOS:A1995QD41900016

ISSN

0740-3232

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