Expand this Topic clickable element to expand a topic
Skip to content
Optica Publishing Group
Journal Home About Issues in Progress Current Issue All Issues Feature Issues

Long-range plasmonic directional coupler switches controlled by nematic liquid crystals

D. C. Zografopoulos and R. Beccherelli

Open Access Open Access

Abstract

A liquid-crystal tunable plasmonic optical switch based on a long-range metal stripe directional coupler is proposed and theoretically investigated. Extensive electro-optic tuning of the coupler’s characteristics is demonstrated by introducing a nematic liquid crystal layer above two coplanar plasmonic waveguides. The switching properties of the proposed plasmonic structure are investigated through rigorous liquid-crystal studies coupled with a finite-element based analysis of light propagation. A directional coupler optical switch is demonstrated, which combines very low power consumption, low operation voltages, adjustable crosstalk and coupling lengths, along with sufficiently reduced insertion losses.

© 2013 Optical Society of America

Full Article  |  PDF Article
More Like This
Directional coupling in long-range dielectric-loaded plasmonic waveguides

Vladimir A. Zenin, Zhanghua Han, Valentyn S. Volkov, Kristjan Leosson, Ilya P. Radko, and Sergey I. Bozhevolnyi
Opt. Express 21(7) 8799-8807 (2013)

Comparative study of directional couplers utilizing long-range surface plasmon polaritons

Triranjita Srivastava and Arun Kumar
Appl. Opt. 49(12) 2397-2402 (2010)

Dual-band electro-optic polarization switch based on dual-core liquid-crystal photonic crystal fibers

Dimitrios C. Zografopoulos, Alexandros K. Pitilakis, and Emmanouil E. Kriezis
Appl. Opt. 52(26) 6439-6444 (2013)

View More...

Supplementary Material (2)

Media 1: MOV (1680 KB)     
Media 2: MOV (1650 KB)     

Cited By

Optica participates in Crossref's Cited-By Linking service. Citing articles from Optica Publishing Group journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (9)
Fig. 1
Fig. 1 (a) Cross-sectional view of the proposed LC-based plasmonic directional coupler and definition of material and structural parameters. Alignments layers (not shown) promote strong anchoring of the LC molecules along the z–axis at the LC/PMMA and LC/polymer interfaces. (b) Definition of tilt and twist angles that describe the nematic director local orientation. (c) Three-dimensional view of the proposed coupler. The coupling length is equal to LC and the separation between the two metal stripes is dC.

Download Full Size | PDF

Fig. 2
Fig. 2 (a) Tilt and (b) twist angle profile in the LC-layer for an applied voltage VLC = 2 V and a stripe separation equal to 3 and 7 μm. (c) Electric potential distribution plotted in the section between the silica substrates for dC = 3 μm.

Download Full Size | PDF

Fig. 3
Fig. 3 Maximum tilt and twist angles in the voltage range between VLC = 1.5 and 2.5 V for a stripe separation from dC = 1 to 10 μm. Shorter values of dC lead to higher twist angles owing to stronger interaction of the electrostatic field with the grounded Au stripe and opposite ITO that define the bar port.

Download Full Size | PDF

Fig. 4
Fig. 4 Modal effective indices for the two TM-polarized supermodes supported of the coupler structure in the rest state (VLC = 0) as a function of the separation dC, and corresponding coupling length LC, defined as LC = 0.5λ0/Δn, where Δn = nsym − nasym, for λ0 = 1.55 μm.

Download Full Size | PDF

Fig. 5
Fig. 5 Electric field modal profiles for the (a) symmetric and (b) anti-symmetric coupler supermodes for dC = 7 μm and the (c) polymer and (d) LC-excitation modes.

Download Full Size | PDF

Fig. 6
Fig. 6 Crosstalk evolution along a total propagation distance equal to 2LC for three excitation scenarios: launching the polymer-input LRSPP mode (Fig. 5(a)), the LC-input LRSPP mode (Fig. 5(b)), or a superposition of the two coupler supermodes (Fig. 5(c–d)). The separation dC is equal to 7 μm.

Download Full Size | PDF

Fig. 7
Fig. 7 Crosstalk values and insertion losses for the cross-state of the coupler as a function of stripe separation dC for the two realistic excitation scenarios under study.

Download Full Size | PDF

Fig. 8
Fig. 8 Crosstalk evolution for the two excitation scenarios at VLC = 0 and VLC = VC = 1.954 V, which correspond to operation in the CROSS and BAR state, respectively, for a propagation distance equal to the coupling length LC = 2.275 mm. Inset shows the insertion losses of the component for both operation states and excitation profiles.

Download Full Size | PDF

Fig. 9
Fig. 9 Optical power propagation at 100 nm above the metal stripes for the (a) cross and (b) bar operation states calculated for the LC-excitation scenario, with parameters as in Fig. 8. The associated multimedia files monitor power coupling at the coupler’s cross-section for the (a) cross ( Media 1) and (b) bar ( Media 2) state.

Download Full Size | PDF

Equations (2)

Equations on this page are rendered with MathJax. Learn more.

e o ( x , y , z ) = ∑ m γ m e m ( x , y ) exp ( − j n eff ( m ) k 0 z ) ,
γ m = ∬ A ∞ e i × h m * ⋅ z ^ d S ∬ A ∞ e m × h m * ⋅ z ^ d S .
Select as filters
Select Topics Cancel
Top
       
© Copyright 2024 | Optica Publishing Group. All rights reserved, including rights for text and data mining and training of artificial technologies or similar technologies.
Privacy | Terms of Use