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Proceedings Paper

Integrated model of liquid crystal-clad waveguide for non-mechanical beam steering
Author(s): H. G. Gotjen; J. Kolacz; C. P. McGinty; A. Clabeau; R. Y. Bekele; J. D. Myers; J. A. Frantz; C. M. Spillmann
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Paper Abstract

The heightened demand for non-mechanical approaches to beam redirection and steering has led to several electro-optical approaches. One with great potential integrates liquid crystal (LC) as a cladding layer to a planar waveguide for continuous two dimensional steering. The birefringence of LC is leveraged to tune the waveguide effective leading to refractive steering, while efficient coupling with a freespace beam is accomplished with a “tapered gap” prism coupler. The out-coupled beam can be steered by refraction in a continuous manner to follow a path or address random points with sub millisecond response times. This device architecture presents a challenge for modeling and simulation with a large parameter space. Experimental successes have motivated a custom MATLAB model that couples LC and waveguide physics. The model simulates the distortion of the nematic LC and uses the graded index profile at the cell boundary to solve the waveguide equation as a function of applied voltage. Raytracing methods are used to track the refraction of an input beam through regions of tunable waveguide index and predict the angular field of regard (FOR). Numerical simulations of the coupling region predict the coupling efficiency given the conditions of the input beam including arbitrary bandwidth. Comparison of coupling conditions and FOR measurements with empirical results allows us to rapidly prototype a device by optimizing parameters with fast algorithms that maximize the field of regard and throughput efficiency.

Paper Details

Date Published: 16 September 2019
PDF: 8 pages
Proc. SPIE 11129, Infrared Sensors, Devices, and Applications IX, 111290O (16 September 2019); doi: 10.1117/12.2529772
Show Author Affiliations
H. G. Gotjen, U.S. Naval Research Lab. (United States)
J. Kolacz, U.S. Naval Research Lab. (United States)
C. P. McGinty, U.S. Naval Research Lab. (United States)
A. Clabeau, U.S. Naval Research Lab. (United States)
R. Y. Bekele, U.S. Naval Research Lab. (United States)
J. D. Myers, U.S. Naval Research Lab. (United States)
J. A. Frantz, U.S. Naval Research Lab. (United States)
C. M. Spillmann, U.S. Naval Research Lab. (United States)

Published in SPIE Proceedings Vol. 11129:
Infrared Sensors, Devices, and Applications IX
Paul D. LeVan; Priyalal Wijewarnasuriya; Ashok K. Sood, Editor(s)

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