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Proceedings Paper

Polarization-insensitive, stacked, liquid crystal polarization grating bandpass filters
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Paper Abstract

We introduce a polarization-insensitive tunable bandpass filter design having the following unique properties: (i) high peak transmittance (~ 80 - 90%) that is independent of input polarization, (ii) non-mechanical tuning over a potentially large wavelength range (> 100 nm) with a narrow passband (< 10 nm possible), (iii) low-cost, simple, and compact (thin-film) construction with a large clear aperture suitable for many simple camera systems. This is a stacked birefringent filter approach similar to Lyot and Solc fiters but with significantly less loss due to the removal of polarizers from the system. The filter is based on a stacked configuration of polymer polarization gratings (PGs) and either fixed or tunable wave plates. PGs are a class of thin film anisotropic diffraction gratings, which exhibit unique properties including zero-order transmittance that is independent of incident polarization, and practically all diffracted light appears within the zero- and first-diffraction orders with efficiency ranging from nearly 100% to 0%. In this work we explore a variety of filter stack configurations and analyze them theoretically using Jones Calculus and Poincare Sphere reasoning. Both fixed and tunable filter configurations are presented and analyzed in terms of finesse, full width at half maximum, free spectral range, and tuning range. We then present preliminary experimental data for a three stage fixed bandpass filter.

Paper Details

Date Published: 23 February 2011
PDF: 9 pages
Proc. SPIE 7934, Optical Components and Materials VIII, 79340V (23 February 2011); doi: 10.1117/12.875473
Show Author Affiliations
Elena Nicolescu, North Carolina State Univ. (United States)
Michael J. Escuti, North Carolina State Univ. (United States)

Published in SPIE Proceedings Vol. 7934:
Optical Components and Materials VIII
Michel J. F. Digonnet; Shibin Jiang; John W. Glesener; J. Christopher Dries, Editor(s)

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