We have developed an all-optical method to control the in- and out-of-plane spatial orientation of nematic liquid crystal
(NLC) molecules by leveraging the highly localized electric fields produced in the near-field regime of gold nanoparticle
(AuNP) layers. A 1-2 micron thick NLC film is deposited on a close-packed drop-cast AuNP layer, excited with tunable
optical sources and the transmission of white light through it analyzed using polarization optics as a function of incident
light wavelength, excitation power and sample temperature. Our findings, supported by simulations using discrete-dipole
approximations, establish the optical switching effect to be repeatable, reversible, spectrally-selective, operational over a
broad temperature range, including room temperature, and requiring very small on-resonance excitation intensity (0.3
W/cm2). For the case of the in-plane switching we have additionally demonstrated that controlling the incident excitation
polarization can continuously vary the alignment of the NLC molecules, allowing for grayscale transmission.
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