Bonding, antibonding and tunable optical forces in asymmetric membranes

Alejandro W. Rodriguez, Alexander P. Mccauley, Pui Chuen Hui, David Woolf, Eiji Iwase, Federico Capasso, Marko Loncar, Steven G. Johnson

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20 Citations (Scopus)

Abstract

We demonstrate that tunable attractive (bonding) and repulsive (anti-bonding) forces can arise in highly asymmetric structures coupled to external radiation, a consequence of the bonding/anti-bonding level repulsion of guided-wave resonances that was first predicted in symmetric systems. Our focus is a geometry consisting of a photonic-crystal (holey) membrane suspended above an unpatterned layered substrate, supporting planar waveguide modes that can couple via the periodic modulation of the holey membrane. Asymmetric geometries have a clear advantage in ease of fabrication and experimental characterization compared to symmetric double-membrane structures. We show that the asymmetry can also lead to unusual behavior in the force magnitudes of a bonding/antibonding pair as the membrane separation changes, including nonmonotonic dependences on the separation. We propose a computational method that obtains the entire force spectrum via a single time-domain simulation, by Fourier-transforming the response to a short pulse and thereby obtaining the frequency-dependent stress tensor. We point out that by operating with two, instead of a single frequency, these evanescent forces can be exploited to tune the spring constant of the membrane without changing its equilibrium separation.

Original languageEnglish
Pages (from-to)2225-2241
Number of pages17
JournalOptics Express
Volume19
Issue number3
DOIs
Publication statusPublished - 2011 Jan 31
Externally publishedYes

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ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

Rodriguez, A. W., Mccauley, A. P., Hui, P. C., Woolf, D., Iwase, E., Capasso, F., Loncar, M., & Johnson, S. G. (2011). Bonding, antibonding and tunable optical forces in asymmetric membranes. Optics Express, 19(3), 2225-2241. https://doi.org/10.1364/OE.19.002225