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Optical Engineering

Dynamic holographic telecommunications components based on spatial light modulation with pixelated x2 polymers in a Fabry-Perot cavity
Author(s): Adam D. Cohen; Robert J. Mears
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Paper Abstract

The provision of a range of wavelength division multiplexing (WDM) network component functionalities by ferroelectric liquid crystal (FLC) spatial light modulators (SLMs) has already been demonstrated in both transmissive and reflective arrangements. The FLC-SLM reconfiguration rate is limited to ~100 kHz by the liquid crystal response time. x(2) nonlinear optical polymers (NLOPs) might form the material basis of a future generation of faster and less costly SLMs for WDM applications, with response time limited only by electronic RC product. We present a theoretical analysis and the experimental characterization of single-pixel SLMs based on an ~2-?m film of commercially available x(2) NLOP in an asymmetric Fabry-Perot (AFP) cavity. Rigorous modeling enables optimization of the generic pixel design and specific pixel parameters, with the design guidelines and constraints dictated by the context of wideband WDM operation ~1.55 ?m. Polymer films are poled at a low field of ~35 V/?m and a 10-V modulating signal is applied. A modulation depth of 1.4% is provided by an AFP device of optimal pixel structure. Further characterization reveals a 3-dB width of transmitted intensity modulation ~10.8 nm near 1.55 ?m. The modeled behavior is extrapolated to yield two significant performance indicators. One indicator is that the holographic diffraction efficiency n of a full-scale pixelated AFP NLOP-SLM will be principally phase-modulation-dependent if the polymer Pockels coefficient r13 is of the order of 5 pm/V. For the preferred reflective geometry, the diffraction efficiency has a maximum value of ~13.5% cf. ~40% for a binary phase FLC-SLM. The second indicator is that for experimental devices, the 3-dB bandwidth of n~1.55 ?m will be only ~5 nm, but a~190 nm-thin cavity-optimized structure will have y3dB of ~30 nm.

Paper Details

Date Published: 1 March 2000
PDF: 10 pages
Opt. Eng. 39(3) doi: 10.1117/1.602408
Published in: Optical Engineering Volume 39, Issue 3
Show Author Affiliations
Adam D. Cohen, Univ. of Cambridge (United States)
Robert J. Mears, Univ. of Cambridge (United Kingdom)

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